|“||I’m going to become a Harem-King!||”|
– Issei Hyoudou shouting out his dreams, Volume 1, Life 2
Issei Hyoudou is the main male protagonist of High School DxD. He is a third-year high school student at Kuoh Academy in Class 3-B and a member of the school's "Perverted Trio", a trio of the most perverted men in the entire student body.
He's a member of the Occult Research Club, and his rank in Rias' peerage is Pawn. His power as a Devil ranks at the bottom at the beginning (which increases as the series progresses, until eventually he becomes the strongest among the young Devils and develops his strength into SS-Class); however, on his left arm, he wields the Sacred Gear, Boosted Gear, making him a dangerous opponent to underestimate. He has achieved his goal of becoming a High-Class Devil, obtaining his own servants, and is one step closer to owning a harem, becoming a "Harem King".
Issei is a high school student of average height with short spiky brown hair, with two short locks of hair behind his head, and light brown eyes. Following his training with Tannin in Volume 5, he gained a more muscular and toned build.
While he has worn various outfits throughout the series, his most commonly worn outfit is the Kuoh Academy boys' school uniform, which consists of a blazer (more commonly black, although in other media is shown with a tinge of purple or grey, with white accents) over a white, long-sleeved dress shirt with black highlights with a black ribbon on the collar, matching black pants, and brown dress shoes. However, Issei's uniform differs in the fact that he wears a red T-shirt underneath his open dress shirt and blazer, and wears blue and white sneakers in place of dress shoes.
From the end of Volume 2 to the beginning of Volume 12, Issei's left arm was transformed into that of a Dragon. In order for it to appear human, a ritual would be performed where Rias or Akeno would suck the power of the Dragon out of it, allowing it to appear human for a few days. After gaining a new body in Volume 12 through the combined efforts of Great Red and Ophis, he is now able to freely transform any part of his body into that of a Dragon.
He has been said to show manly expressions by his paternal grandmother. Issei's height is 170 cm (5 feet 7 inches) and body weight is 62→65 kg (137→140 lbs.).
Issei has many personality traits. Issei is first shown to be ignorant, self-centered, arrogant, and his ongoing perverted nature, often to make lecherous fantasies, and utterly obsessed with women's breasts and having his own harem. This has caused him to be instantly labeled as a pervert among the girls of Kuoh Academy and has gained him notoriety for being one of the members of Kuoh Academy's Perverted Trio.
Despite his pervertedness, Issei is kind, courageous, and unwaveringly determined of wanting to protect those who are important to him despite almost dying by the hands of his opponents. He's also very caring, "putting his nose into other people's business" as he helped Yuuto Kiba, Koneko Toujou, and Akeno Himejima overcome their fears and hatred of their mournful past. Due to this, he gained strong friendship from his comrades and affection from most girls of the Occult Research Club. He is, however, oblivious to the feelings of the girls around him (save for Rias after his confession), often believing they are simply teasing him. Even with Rias' family telling him to use the same titles for them as Rias (Father, Mother, Brother, etc.) and other mentions of engagement activities, he still remains the same. This is due to his trauma with Raynare. He has a habit as mentioned by his mother of not forgiving himself if he does something wrong: always saying sorry if said thing is mentioned, and showing an expression of pain and regret.
After his murder by Raynare, Issei had developed a fear of admitting his feelings to the girls, as he thought it would cause them to turn their backs on him. He acknowledged that this would never happen, but it was still an intense fear. However, by Volume 10, that fear had been overcome. Even with the knowledge that the girls do have romantic affection for him, he still has problems acknowledging some of their ongoing rivalries, an example being who gets to sit on his lap.
In battle, Issei is sometimes very stubborn, and due to his emotions, he often charges ahead towards his enemies without a second thought whenever his comrades are insulted, treated badly, or easily defeated. Azazel has stated that it is one of Issei's bad habits. Lately, he has started to become more tactical in his battles, using technique-type strategies to defeat opponents, as shown when he used the abilities of the Wyverns in a unique way to defeat Euclid. Another sign of his kind nature is that despite wanting to lose his virginity, Issei refuses to take advantage of women when they are upset, even if they themselves are willing to. This happened when Akeno appeared in front of him naked and wanted to have sex to forget about her sad past and her father. However, Issei refused, knowing it will just hurt her more, and put her clothes back on and hugged her to comfort her.
Before Issei's birth, his mother became pregnant twice, but the pregnancies ended in miscarriages. So when Issei's mother got pregnant for the third time, his father had paced back and forth in front of a Shinto shrine honestly wishing that this time they would succeed. When the newborn was finally born he was named Issei, meaning "honesty", for his father's honest prayers.
He is a childhood friend of Irina Shidou and they would always play together before she moved to England, although he thought she was a boy at the time. At some point when Issei came over to Irina's house, she kissed him while he was sleeping. Sometime during his childhood, Issei met an old man who told him and other children stories about breasts, which eventually led to Issei's fascination with them and his perverted tendencies.
He attended the same middle school with Matsuda and Motohama and the three of them started attending Kuoh Academy one year before the story, and have come to be known as the Perverted Trio to just about the entire school.
Issei was introduced in Volume 1 of the light novels, where he is asked by Yuuma Amano to go on a date with her. However, at the end of the date, Yuuma suddenly kills him, after revealing herself as a Fallen Angel in the process. In his dying moments, Rias Gremory arrives and saves his life, after he inadvertently summoned her whilst thinking about her. The next day, after noticing some strange changes within his body, he is attacked by the Fallen Angel Dohnaseek, who critically wounds him until Rias Gremory arrives and saves him once more. He is then introduced to the other members of the Occult Research Club: Yuuto Kiba, Koneko Toujou, and Akeno Himejima, and soon learn that all of them, including Rias, are Devils. He soon learns to his surprise that he is a Devil as well. However, after learning from Rias that he can one day have his own servants, Issei then declares his dream to have his own harem, becoming a "Harem King". Later on, he meets Asia Argento, a nun, and quickly befriends her. He soon learns that she, too, possesses a Sacred Gear after using it to heal a young boy. He then guides her back to the Church, where, upon reaching near it, he gets strange chills coming from his body, forcing him to stop while Asia goes on ahead (Rias explains to him that Devils cannot go near churches as there is a risk of getting killed by the Angels' light spears).
During his first-ever battle with the Stray Devil Viser, he learns from Rias about Kiba, Koneko, and Akeno's respective traits as Knights, Rooks, and Queens, and later learns, to his disappointment, that he is a Pawn. The next night, Issei goes on another run to meet up with a client, only for the client to be killed by Freed Sellzen, a stray exorcist, upon arriving at the client's home. He is nearly overwhelmed by the berserk priest until Asia intervenes, pleading Freed to let Issei go but gets hit by him, angering Issei who fights Freed one more time but is stopped when the rest of the Occult Club intervene to bring Issei back. Fortunately, Issei eventually meets Asia again at a nearby park the next day, and the two spend the entire day together which ends with the sudden appearance of Raynare who takes Asia back after overwhelming Issei despite the latter using his Sacred Gear.Determined to save Asia from the Fallen Angel, Issei, with Kiba and Koneko's help, manages to reach the church where Raynare is hiding while fighting Freed once more. However, it was too late and Raynare takes Asia's Twilight Healing. Escaping with Asia, Issei shares one last conversation with her who thanked Issei for being her friend as she dies in his hand. Determined to avenge Asia's death, Issei fights Raynare in a one-on-one duel, while initially having difficulties he successfully defeats her after activating his Sacred Gear, the Longinus, Boosted Gear's true ability. He then allows Rias to kill Raynare after the latter desperately begged Issei to save her, even going as far as saying she loves him, having seen through her ruse. After the battle, he was delighted after Rias revives Asia as one of her Bishops, sharing an emotional reunion with Asia. The next day, Issei was surprised to see Asia dressed in a Kuoh Academy uniform as Rias informs Issei that Asia has been transferred into the school and will be in Issei's class.
At the beginning of Volume 2, while having a dream about marrying Rias, Issei encountered a Red Dragon in that dream waking up shortly after. Following his daily training with Rias, Issei was shocked to learn from her that Asia will be moving in to stay with him as Rias successfully convinces Issei's parents to let Asia stay. A few days later, while getting used to Asia being at his house while having his usual school life and Devil's job, Issei gets a sudden visit from Rias, who asks to take her virginity much to his shock and surprise. Unfortunately, Rias' attempt is foiled with the appearance of Grayfia Lucifuge, a maid from the Gremory, who scolds Rias for attempting to break off the engagement set by her brother and father. Later on, Issei meets Riser Phenex, a man from the Phenex Clan who, to his shock, is revealed to be Rias' betrothed. Refusing to accept it, he activates his Boosted Gear in an attempt to face Riser one-on-one but is easily defeated by one of his Pawns.
After Rias agrees to face Riser in a Rating Game with her engagement on the line, Issei and the rest of the Occult Research Club members go to a mountain to train. He later assisted Rias in her first-ever Rating Game against Riser, in which he incapacitated three, defeated one and assisted in defeating five of Riser's Peerage before going off to face Riser. Issei, however, was incapable of doing anything as his body reached its limit due to the burden of the boosted power that is continuously placed on his body, and was nearly beaten to death by Riser, forcing Rias to resign. Later waking up in his room and being informed of Rias' defeat by Grayfia, Issei becomes frustrated and blames himself for his weakness only to be given a paper with a magic circle engraved on it by Grayfia. Arriving in the engagement party hall, Rias' brother and Satan, Sirzechs Lucifer, reveals that he set up this event as an entertainment for Rias' engagement party, which allows Issei to battle Riser one more time in a one-on-one fight with Rias' engagement on the line, and won through the strategy he formulated beforehand. Taking Rias away from the ceremony, Rias thanks Issei for what he did, kissing Issei for the first time.
In Volume 3, Issei wakes up to a chaotic morning due to Rias who now stays with him. During the club meeting held in Issei's house due to the cleaning of the old school building, Issei's mother shows Issei's childhood photos to his friends; among them include a photo of Issei and his childhood friend, Irina Shidou, which has a Holy Sword in it, with Kiba seeing the photo and remembering his revenge. He was then introduced to the Student Council members led by Sona Sitri, whom it was revealed is a High-Class, Pure-blooded Devil and the heiress of the Sitri Clan. While preparing for the ball tournament of Kuoh Academy, Issei starts to notice the change in Kiba, pressuring Kiba into revealing what is going on as Kiba reveals his goal in life, revenge on the Excalibur, as Issei learns of the ongoing situation between Kiba and the Excalibur sword. He later re-encounters his childhood friend, Irina, who is now under the Church's orders to retrieve the stolen Excalibur swords. Having found out about Yuuto's past, Issei decides to help the latter to overcome his past. To that end, Issei, Koneko, and Genshirou Saji went to find Irina and her partner Xenovia and made a temporary alliance with the Church Duo, where they will help the two of them to retrieve the Excaliburs in return for allowing Yuuto to destroy them. They eventually encounter both Freed Sellzen and Valper Galilei, engaging in a battle with the two of them who manages to escape. Their alliance was then found out by their masters and the three of them are punished for taking this action without their consent. The Occult Research Club was then confronted by Fallen Angel leader, Kokabiel who challenged the Gremory Team to a fight within the grounds of Kuoh Academy. With backup from the Sitri Team who formed a barrier surrounding the school, the Gremory Team engaged Kokabiel, Freed, and Valper. While the Gremory Team and Xenovia were able to defeat the Cerberus sent by Kokabiel and Freed who was wielding the Fused Excalibur, they eventually engaged Kokabiel in a battle and were overwhelmed by the latter who revealed the death of the Biblical God. The Gremory Team, however, were saved by the sudden interference of Vali Lucifer, who came to retrieve Kokabiel and Freed under Azazel's orders.
In Volume 4 of the light novels, Rias introduced her other Bishop, Gasper Vladi, to Issei, Asia, and Xenovia. Issei later helps in Gasper's training on how to use his Sacred Gear. Prior to the meeting of the Three Factions, while visiting Akeno at the shrine she used to stay at, he receives St. George's Dragon Slayer sword, Ascalon, from the Archangel Michael, and learned of Akeno's identity. He later assisted in fending off the Khaos Brigade members who came to kill the leaders of the Three Factions during the peace negotiations, as he and Rias go to rescue Gasper who was being used by the Khaos Brigade. After successfully rescuing Gasper from the Khaos Brigade, Issei, Rias, and Gasper are surprised at the sudden betrayal of Vali Lucifer who then goes on to fight Issei. Using the bracelet given to him by Azazel, which act as a substitute for the sacrifice needed to use the Scale Mail, he begins his duel with Vali. While initially incapable of doing much against Vali, Issei uses Ascalon to break Vali's shield and manages to transfer Ddraig's power to Vali's Scale Mail, forcing it to temporarily stop its function and land an attack on Vali. Issei, however, was shocked at the recovery rate of Vali's Scale Mail and with few options left, Issei decides to take a risk by implanting Albion's power to the Boosted Gear, which was successful and created the Dividing Gear. Vali, who was interested at the situation, goes on to say that he will halve all of Issei's surroundings, which Azazel adds on that breasts will be halved as well, angering Issei to the point that he is able to overwhelm Vali in his usual Balance Breaker form. The battle, however, was ended abruptly by the sudden intrusion of Bikou who came to retrieve Vali before he could activate his Juggernaut Drive.
In Volume 5, he goes to the Underworld with Rias and his friends for the Young Devils Gathering. Upon arriving at the Gremory region, Issei, along with Rias and her peerage, is greeted by the servants of the Gremory household before meeting Rias' mother, Venelana Gremory, and nephew, Millicas Gremory. During that time, he was taught how to read and write the Devils' alphabet, proper table manners, dance classes and how to interact with people with high social status. Before the ceremony for the Young Devils Gathering, Issei meets the four other Devils that are chosen for the competition: Sairaorg Bael, Seekvaira Agares, Zephyrdor Glasya-Labolas, and Diodora Astaroth. After the Rating Game between Rias and Sona was determined, he was forced to train with the former Dragon King, Tannin, in one of the mountains in the Gremory region, and obtained a great stamina that he can use when he gained his Balance Breaker. Issei, however, did not attain his Balance Breaker until the fight against Kuroka and Bikou where he gained full access to his Balance Breaker after poking Rias' breasts. He then assisted Rias in her Rating Game against Sona. While he manages to defeat Saji, he lost due to blood loss which was set up as a plan by the Sitri Group to defeat Issei. Before disappearing, however, Issei reveals his new move, Pailingual, which allows him to talk with female breasts and learned of the Sitri Group's strategy, allowing Rias' team to win the match in the end. While the Occult Research Club is leaving the Underworld to head back to the human world, the group was surprised by the sudden appearance of Diodora Astaroth, a Devil whom Asia healed in the past, who came to propose to Asia.
In Volume 6, Issei and his friends accompany Rias to the television station of the Underworld for an interview for the Young Devils Tournament where they met Sairaorg and his Queen, Kuisha Abaddon, who just finished their interview and told the Gremory Team that he wants to face them with pure power only. During Rias and Diodora's scheduled Rating Game, the match was interfered by the sudden appearance of the Khaos Brigade and the revelation of Diodora's alliance with them before kidnapping Asia. The Gremory Team would then go on to defeat Diodora and his peerage and rescue Asia until the sudden appearance of Shalba Beelzebub who sends Asia to the Dimensional Gap. This act caused Issei to activate the Juggernaut Drive of the Boosted Gear, due to the negative feelings that appear after the apparent "death" of Asia and made him go berserk. He defeated Shalba, even biting off his left hand, but was incapable of stopping himself until Azazel and Sirzechs composed an Oppai Dragon song and used Rias' breasts as a switch to help him release the Juggernaut. Issei then witnessed the appearance of the Great Red, who was swimming in the Dimensional Gap, later falling unconscious. He wakes up in his room, having a discussion with Sirzechs through hologram regarding Juggernaut Drive. He then runs with Asia on their three-legged race and receives cheers from Occult Research Club members and Azazel. After winning first place, Asia tends to Issei behind the gym, where she kisses him and confesses that she loves him.Volume 7, Issei goes on a date with Akeno, which ends with both of them meeting Odin, Rossweisse, and Baraqiel, Akeno's father and Fallen Angel leader, who served as Odin's bodyguard at that time. The Occult Research Club is then attacked by Loki who came to kill Odin and create Ragnarok. Issei faces off against Loki in a fight but was dominated by the arrival of Fenrir. Issei and his friends are, however, saved by the timely arrival of Vali Lucifer and his team. The two teams eventually decided to work together to fend off Loki and Fenrir, asking the advice of the Dragon King, Midgardsormr, on how to defeat Loki and Fenrir. During the final battle against Loki, Issei wielded a replica version of Mjolnir, a hammer used by Norse God Thor. While initially incapable of fully using the Mjolnir, Issei gains the ability to use it after helping Akeno reveals her true feelings and make amends with her father through the help of the Breast Fairy send by the Chichigami, adding with the Holy Lightning of Baraqiel and Akeno and allowing them to defeat Loki. The group later returned to their clubroom where Akeno kisses Issei and confesses that she loves him in front of everyone, which only angers the other girls.
In the Extra Life of Volume 8, Issei and Rias went the Underworld and underwent a ceremony at the Ruins of Connection to test his suitability as Rias' future husband. Throughout the ceremony, Issei and Rias faced four trials set up by the Satan Rangers. In the first trial, Issei and Rias had to dance; in the second trial, they were tested on table manners; and in the third trial, on the history of the Gremory Clan and general knowledge in the Underworld, all of which they successfully passed before moving to the final trial. In the final trial, Issei was forced to fight Sirzechs/Satan Red and was completely overwhelmed by the latter, until Grayfia's advice on using Rias' breasts as a power-up allowed Issei to use one final Dragon Shot, but still lost after Sirzechs negated the attack and retreated after Issei loses consciousness. After the ceremony, Ajuka Beelzebub, one of the Four Satans and the original creator of the Evil Pieces system, remodeled Issei's Piece to adapt to the powers of Ddraig.
In Volume 9, Issei and the rest of the second-year students go to Kyoto for their school trip. In the train, Issei enters the depths of the Boosted Gear, where he meets one of the past possessors of the Boosted Gear who provides him with a box that unlocks his potential and its possibilities. During the trip, Issei was attacked by several Youkai led by Kunou, who thought that he is the one responsible for capturing her mother, Yasaka, the leader of the Youkai. While they manage to clear off the misunderstanding, Issei and his friends are soon confronted by the culprits who captured Yasaka: the Hero Faction led by Cao Cao. While the first fight was cut short by the interference of Le Fay Pendragon and Gogmagog from the Vali Team, Issei and his friends are forced to face off with the Hero Faction one more time to rescue Yasaka from them.
During the fight, after seeing one after another of his friends being defeated, Issei curses his own powerlessness again, but this time with Belzard and Elsha's advice, Issei successfully achieved the Illegal Move Triaina due to his desire to protect his friends and Rias' breasts, allowing him to change the Scale Mail armor through Promotion. With the new found power, Issei manages to temporarily overwhelm the entire Hero Faction before succumbing to the exhaustion. The team, however, was rescued by the sudden appearance of Sun Wukong who fends off the Hero Faction and using his Senjutsu to rejuvenate Issei, allowing him to use one more attack, which he landed on Cao Cao's eye. After coming back from Kyoto, the team was scolded by Rias for not calling her to help them, before Azazel tells the group that Ravel is transferring to the Kuoh Academy, much to the dismay of the girls of the Occult Research Club.
In Volume 10, after finishing another Oppai Dragon campaign, Issei and Rias met Rias' mother, Venelana, who complimented them for their hard work, before scolding Rias for her lack of progress with Issei. Rias would then attempt to seduce Issei by trying to have sex with him in the sauna room of the Hyoudou Residence. Issei, however, fails to understand and calls Rias "President", greatly saddening and angering the girl, asking him what is she to him. He later reveals to Koneko, Asia, and Akeno (who are trying to "heal" him) that his experience with Raynare made him fear women, after he planned his whole first date with her, only to be killed and treated terribly, made him afraid to call girls by their first name, and also afraid of being disliked by other girls or rejected if he showed his feelings again. The girls, however, quickly objected to this, and Raynare's "curse" is lifted from Issei's heart.
During Rias' Rating Game against Sairaorg Bael, Issei fought against Sairaorg's Bishop, Coriana Andrealphus, and Queen, Kuisha Abaddon, both of whom he defeats, before facing off against Sairaorg and his Pawn, Regulus, in the final match with Rias. During the match, Issei was doing well against Sairaorg until Sairaorg fused with Regulus to use his Balance Breaker, overwhelming Issei. Issei, however, was able to overturn the situation by gaining access to the True Queen, achieving Cardinal Crimson Promotion which combines the power of the Rook, Knight, and Bishop to his Balance Breaker armor while changing it to crimson. Using his newly acquired powers, Issei manages to fight on par with Sairaorg, successfully defeating the man in a fist fight. After Sairaorg lost consciousness, Issei hugged him, saying his thanks, before passing out. Following his victory, Issei cannot hold back his feelings for Rias and confesses to her, calling her by her first name for the first time. She accepts his feelings in tears of joy and the two officially become a couple, although it seems none of the other girls (Akeno, Xenovia, Asia, Koneko, Irina, and Ravel) have given up on Issei.
In Volume 11, Issei, like the rest of the Gremory Team, are surprised to see Ophis, accompanied by Le Fay and Kuroka, come to their house, which was set up by Azazel after Ophis claims that she wants to observe Issei. Later, Issei, Akeno, and Yuuto go to the Glasya-Labolas territory to take the promotion test to become Middle-Class Devils. While the group is resting after the test, they are ambushed by Cao Cao and Georg who came to steal Ophis' powers. The battle ended with the Gremory and Vali Teams losing to Cao Cao and Ophis' powers stolen. Both teams were then attacked by a legion of Grim Reapers and Siegfried. They eventually overcame the situation by having Issei use Rias' breasts to replenish Issei's magic and successfully force their enemy to retreat, until Shalba appeared with a kidnapped Leonardo, forcefully activating Leonardo's Balance Breaker, which creates 13 gigantic monsters to destroy the Underworld, and kidnapped Ophis.
Near the end of the volume, Issei went to rescue the kidnapped Ophis from Shalba who escaped into a crumbling dimension field. Issei eventually caught up to Shalba and the two of them fought one last time before Issei kills him. During the fight, however, Shalba manages to inject an arrow infused with Samael's blood, which led to Issei's death.
In Volume 12, Issei's original body is destroyed due to Samael's curse, but he then gains another body with the help of the Great Red and Ophis. He returns and successfully saves the child who was taken hostage by Jeanne and Heracles, defeating the former easily. He has his third encounter with Cao Cao but was easily outmatched by the latter, even with Rias using her ability to recharge Issei's power, until Issei used a bullet from Gogmagog that has Samael's blood on it, on Medusa's eye, that Cao Cao was using, reversing the situation. In order to turn back the tide of battle, Cao Cao attempts to activate the Truth Idea, but unsuccessfully, as its effects depend on God's will in the Holy Spear, and it will be different depending on what the will chooses. The True Longinus has chosen the wish in Issei's heart, rather than Cao Cao's ambition, thus Cao Cao is defeated. At the end of Volume 12, Issei is officially promoted into a Middle-Class Devil, along with Akeno and Yuuto. Afterward, Rias and Issei plan on going out on a date as promised earlier, with the rest of the Occult Research Club members (including the guys, much to Issei's distress) deciding to come with.
In the Extra Life of Volume 13, Millicas goes to the Hyoudou Residence and temporarily stays with them. He later has a mock battle against Issei, Kiba, and Gasper. Despite losing to them, Issei notes that his power is extraordinary and his talent is said to be the same as that of Vali. Later, when Sirzechs asked him whether he liked Satan Red or Oppai Dragon, Millicas chose the latter. This made Sirzechs sad, and it became worse when he saw Issei and Millicas getting along. In the end, Issei calls him Millicas instead of Millicas-sama. Issei is later given a familiar, the living Norse flying ship Skíðblaðnir, by Surtr Second (which he later names Ryuuteimaru).
In Volume 14, Issei meets the Director of the Magician Council, Mephisto Pheles, regarding the pact between the Occult Research Club and Magicians. He later attended the negotiation with the Vampires who were led by Elmenhilde Karnstein who wanted Gasper to join her clan, the Carmilla Faction. He was completely ignored when he asked her a question due to his status as a servant. Several days later, while attending his class, Issei was attacked by three Stray Magicians who distracted him so that they could kidnap the first-year students of the Occult Research Club. He, along with the other members of the Occult Research Club and the Student Council then go to battle them and easily defeated the Stray Magicians and the Magicians from Khaos Brigade before a voice called Issei, Akeno, Xenovia, Asia, Irina, Rossweisse, Saji, and Sona to meet him. The group was sent to a "factory" built in the Dimensional Gap that was used to create artificial Phoenix Tears using clones of the Phenex Clan. After some talk with the supposed leader, he summons Grendel and Issei was forced to battle him one-on-one but was overpowered throughout the fight until he used Ascalon's Dragon Slayer abilities to turn things around. It was then that the leader of the Magicians, Euclid Lucifuge, Grayfia's younger brother, calls Grendel to retreat while revealing himself to Issei and the others.
In Volume 15, while Issei and Ravel are selecting magicians to make a pact with, Akeno, Sona, and Bennia entered his room to discuss what the Sitri and Gremory groups would do while Rias and Yuuto are in Romania. They did their discussion in the underground pool when Kuroka and Le Fay arrived and were shocked when Kuroka mentioned that they fought the Evil Dragon, Aži Dahāka. Griselda Quarta, Dulio Gesualdo, and Tobio Ikuse later arrived and asked Issei if it is okay for them to help train the group to which Issei happily agreed.
In Volume 16, Issei, along with the Occult Research Club members, Bennia, and Loup Garou went to Romania to aid Rias and Yuuto who were confined in the Tepes castle, reuniting with the two when they arrived at the castle. They were then taken to the throne room to meet the new "King", Valerie Tepes and the new mayor, Marius Tepes as the group was angered by Marius' action and the latter's claim that he could do so without fearing for his life because of his bodyguard, the Evil Dragon Crom Cruach. After the meeting was over, Issei and the others met an old man wearing a Lucifer outfit who he was shocked to learn that the man was Vali's grandfather, Rizevim Livan Lucifer and vehemently refused Rizevim's proposal to join his group.
Issei then participated in the attempt to stop the extraction of the Longinus, Sephiroth Graal, from Valerie and save her. Meeting Grendel again, Issei and his friends team up to battle Grendel in order to buy time for Rias to use her new move, in which they successfully dealt serious damage to Grendel with their combined efforts. The fight, however, ended without a clear outcome, as Crom Cruach appeared and ordered Grendel to retreat. Vali then appeared as both Issei and Vali agree to team up to face the strongest Evil Dragon. Issei in his Cardinal Crimson Queen was able to deal minor damage to Crom Cruach by using Crimson Blaster combined with Ascalon's dragon-slaying ability. The fight was stopped by Crom Cruach since he was told to stall them just for ten minutes. Issei later fought the mass-produced Evil Dragons that were rampaging at the Carmilla's castle town and was able to defeat them easily until he encountered Euclid Lucifuge. He then fought against Euclid who uses a replica of the Boosted Gear. He was overwhelmed by Euclid in his Scale Mail but was able to turn things around when he used his newly found power which allows him to create small white Dragons that can "divide" and "reflect". The fight was stopped when Rizevim and Lilith arrived and told Euclid that it is time to retreat. After returning from Romania, Issei participated in the meeting for the formation of D×D and told Ravel that he wants Le Fay to be his contracted magician.
In Volume 17, Issei was suddenly asked by Rossweisse to act as her boyfriend much to his and the other girls' surprise, the reason of which was later revealed that Rossweisse lied to her grandmother about having a boyfriend. He meets Rossweisse's grandmother, Göndul, as Rossweisse's "boyfriend". He and Rossweisse then go on a date in Tokyo which ended abruptly due to Euclid's sudden appearance. Later, Issei and his friends went to the newly built Auros Academy to help teach the children. During their stay, while Issei is having a bath, Rossweisse joins in due to no hot water in the girls bath, they talk regarding her research on Trihexa, worried that she might be taken and used by the enemy, Rossweise asks Issei to kill her if it were to happen, but he refuses to say that he will protect her. The academy was soon ambushed by Qlippoth, Issei then teams up with Nimura to fend off the mass-produced Evil Dragons before meeting up with Saji and Koneko, as the four are confronted by Grendel and Ladon who proceeds to seal Issei inside his barriers Issei helplessly looks on as Saji and the fathers of the children are attacked ruthlessly by Grendel, until Sairaorg arrives to assist as Ladon was ordered to retreat to Agreas while Grendel remained to fight Sairaorg and Issei who teamed up and successfully defeated Grendel, allowing Koneko to seal Grendel.
Issei regroups with his allies to fend off the remaining Evil Dragons until Euclid appears and kidnaps Rossweisse as Issei and Rias proceed to pursue Euclid. Issei and Rias then confront Euclid regarding his goals as Euclid reveals that he wants to make Rossweisse his "sister" and soon after kills the magicians allied to them by changing them into living bombs, effectively destroying the school. Angered by this act, Issei proceeds to fight Euclid, successfully overpowering him after Issei manages to unlock the Longinus Smasher. After the incident with Qlippoth, which ended with Agreas getting stolen, he and his allies were informed that they are going to Heaven's side to help with something during the winter holidays.
In Volume 18, Issei went to Heaven, alongside the Gremory group. Upon their return home they meet Irina's father Touji Shidou who had come to visit, he brings them a magic doorknob that leads to an Interdimensional Room that allows Irina and Issei to have sex without her falling. While out shopping with Irina, Touji, Xenovia, and Asia, they are confronted by Masaomi Yaegaki who is wielding Ame no Murakumo no Tsurugi infused with half of Yamata no Orochi's soul and seeking revenge on Touji. They all fought against Masaomi but he manages to impale Touji and poison him, he retreats as soon as reinforcements arrive. Touji who is now hospitalized explains that Masaomi was a former subordinate of his who was executed by the Church for being in a romantic relationship with a Devil named Cleria Belial. Later, Issei and the Occult Research Club meet up with Zekram Bael, he then revealed to them that he ordered with the permission of Heaven and the Church the death of the exorcist Masaomi Yaegaki and the High-Class Devil Cleria Belial in order to maintain the status quo that both sides did not want to disturb.
Issei and the rest of the Occult Research club went back to heaven after being contacted by Touji who was transferred there to be cured, he gives Irina the Holy Sword Hauteclere, he has a discussion with Issei alone asking him to take care of Irina. Later during the Qlippoth's sudden invasion on heaven, he fought against Crom Cruach in his True Queen mode, however, Issei was overwhelmed by the latter. His fight ended when Crom Cruach walked away, after losing the will to fight due to Walburga interfering with the fight. During the battle Masaomi came in to kill Touji but was saved by Issei, Irina and Xenovia, they were able to defeat him with the use of their Holy swords, and thus freeing him from the Dragon's influence, Masaomi is then killed by Rizevim which infuriates Issei as he had a slight understanding of him. Issei then proceeded to fight against the latter, however he was overwhelmed by him due to his Sacred Gear Canceler, shortly after Issei was able to use the power of "Penetrate" thanks to Ddraig diving into the depths of the Sacred Gear and recovering a portion of his lost powers, due to his new found power Issei was able to bypass Rizevim's Sacred Gear Canceler and deal Significant damage to him. Right before Rizevim escaped with Lilith, Issei declared that the one to defeat him would be Vali. Later, Issei and Irina went out shopping, She suddenly kisses him and reveals that they've already kissed before as kids. They then meet up with Azazel in a Santa Claus outfit and recall their childhood promise to attack Santa, so with the help of Ophis, they charged at Azazel.
In the Extra Life of DX.1, Issei overhears Rias and Ravel discuss how the Gremory and Phenex Rating Game would've ended if all of Rias current Peerage took part in it, this actually gets everyone interested in finding out which leads Ravel to call Riser for a rematch with Rias which will start on their next holiday. When the Rating Game begins, Issei heads to Gym with Koneko and Xenovia where they faced against Ile, Nel, Mira, and Xuelan. He battles against Mira in his armor and wins by shooting his Dragon Shot which made her naked, before she leaves, Mira asks for his autograph for later. They leave the Gym which was soon destroyed by Akeno and met up with Kiba who goes against Karlamine, as well as Irina who to their surprise fills the place as Riser’s substitute Bishop and faces off with Xenovia. Issei meets up with Ni and Li who want a rematch with him but Koneko, wanting to see specialty in who is superior goes against them instead. Isabela, also wanting a rematch with him becomes his opponent, he fires a gigantic Dragon Shot while Isabela dodges it at first, but she is affected by Issei’s Dress Break and retired after being hit by his redirected Dragon Shot.
Issei is soon escorted by Mihae under Riser's orders to the new school building where their respected masters are, where they meet up with Asia, Gasper, and Rossweisse, Mihae allows him and Asia to pass but fights against Gasper and Rossweisse. They arrive at the rooftop where they see Riser and Rias, Riser requests to fight Issei one-on-one which he also agrees to, they both battle giving everything they’ve got with Issei using his True Queen armor, Riser states that even if he loses to him a hundred times, he is determent to defeat him one day. In the end, the victor goes to Issei and his team. A few days later, Issei again overhears Rias and Ravel discuss Sona’s match with Seekvaira Agares and ask Azazel who would win in a Scramble Flag match between them and Seekvaira which he prepares to call the House of Agares, although Issei is not overwhelmed over the idea.
In Volume 19, Issei and his club members went to Kyoto for New Year’s Day, where he and Rias meets up with Kunou and her mother Yasaka who greet their arrival, although Kunou is upset that Ophis (who she knows as Phis) didn’t come, Issei excuses it that she caught a cold. While Kunou goes to fetch a remedy, Yasaka is glad how close he is with her daughter but asks him to wait until she’s an adult, she teases that until then he can have her instead. At that moment, Kunou returns and interferes by holding onto Issei’s leg. Issei then learns of Rias' previous discussion with Yakasa about Kunou attending middle school at Kuoh Academy in the coming year. Issei heads to the top of the shrine to meet up with his friends who’re giving their prayers, although he is embarrassed by Xenovia’s request to have his children this year, starting to be half-joking while seeing his expression, her wish is actually to have smooth election win or lose and suddenly kisses him for good luck much to his surprise.
At their club room, the group discusses the changes that are happening around them such as Rias and Akeno graduating and how Le Fey and Bennia would be joining. Later, Issei watches Xenovia prepare her campaign with help from Irina, Asia, and Kiryuu who he shockingly discovers is aware that he and his friends aren’t human. Later that night, in the Hyoudou mansion's underground pool, Issei and Rias show off their new technique to members of their club, Vali’s Team, Dulio, Sister Griselda, Tobio, and others. He began rubbing sun lotion onto Rias and Akeno, catching the attention of most of the other girls who also want to take turns with him rubbing lotion on them with Ravel sorting a schedule.
The next day, the gang are visited by Vasco Strada, one of the people leading a rebelling against the Church, he gives Rias a challenge announcing a battle between them and the rebels in three days. Soon after, Tannin paid a visit to the Hyoudou Residence, asking for their assistance in looking after an egg of a rare species of Spectral Dragon and is surprised to see that Crom Cruach is the one delivering the egg, it’s revealed that he is currently under Tannin's care. On the night before the battle, Issei makes his final preparations as he meditates to allow energy to wrap itself around his body while in mid-flight above the pool with his Dragon Wings, Xenovia entered planning to do her usual routine of skinny-dipping. As they talk, Xenovia expressed her worries of being unable to surpass Sona as the Student Council President and Vasco as the wielder of Durandal. Issei then told her that she can do it and asked her why she chose to run as the Student Council President. Xenovia reasoned that she loves Kuoh Academy as it has given a lot to her and she just wants to give something back in return. Xenovia pulled Issei into the pool with her and kissed him a second time and reminded him of her intent to join his peerage once he becomes a High-class Devil.
On the day of the battle against the Church rebels, they gain assistance from the Sitri group and Brave Saints. They split into two teams to defeat the rebel leaders Vasco Strada and Ewald Cristaldi, Issei tells Kiba who requested the fight against Ewald to come back alive. Issei and most of the Gremory group along with Saji take part in the battle against Vasco who proves to be a difficult opponent to defeat even with the help of Kiba and Irina who had just come over from their previous fight and unmatched by Issei’s True Queen armor. Arthur Pendragon, who has been watching from the side, joins in and actually matches Vasco in a sword fight as everyone watches in awe, however Arthur soon leaves, not knowing why as it was something that swordsman could understand. Xenovia, who receive some insight on Durandal from Vasco, splits Excalibur from Durandal, uses both swords in tandem and defeats him. As Vasco allowed himself to be taken prisoner Walburga makes an appearance. Everyone readies their stance against Walburga who summons an army of Evil Dragons, however, to everyone’s surprise, are rendered motionless due to a barrier Rosswiesse set up, her escape route is also cut off by Tobio. Frustrated, Walburga activates her Balance Breaker that manifests the other half of Yamata no Orochi soul from her flames. Everyone gives their best against her with Issei quickly using Reflect, Penetrate, Pailingual and Dress Break on her while others inflict damage to the Evil Dragon. With Xenovia finishing it off with her new move, Cross Crisis, Walburga froze on the spot witnessing her Balance Breaker destroyed, is then hit by Issei’s Crimson Blaster, resulting in her defeat and arrest.
A few days after the battle, the final day of the candidates in the Student Council Election had begun where Saji and Xenovia won Vice-President and Student Council President respectively. Issei met up with Griselda, who came to see the election, who was moved by her “little sister’s” heartfelt speech, they are joined by Xenovia who is surprised to see Griselda and asks for permission to use the Interdimensional room which only angers her. Later, The Occult Research Club gathered in the lab where Valerie was and gave her a piece of the original holy grail that was given to them by Vasco before his arrest which in turn wakes her from her coma. When everything was going well, the group heard the news of Ravel, who had temporarily joined her Brothers Peerage in a Rating Game against Diehauser, has gone missing along with Riser and Diehauser.
In Volume 20, everyone is depressed over the disappearance of Ravel, including Raiser and Diehauser, which they believe that Qlippoth is responsible for, with suspicion of the Champion also being involved. Days later, everyone in Issei’s year have come to school to have a three-way career consultation, he explains to his mother and teacher that he plans on going to Kuoh Academy University and to work under Rias’ father as a career choice and then start his own company, which he has not discussed with his parents yet. The next day, Azazel comes to everyone with the news that Ravel and Raiser have been recovered and are currently under Ajuka’s care. The next day, Issei and Asia visit Ophis who is taking care of the Spectre Dragon egg in a vast open space underneath Kuoh Town, sitting slightly away is Crom Cruach in human form who Asia offers some Banana.
As the D×D Team prepare to depart to visit Ajuka, Issei’s dad invites him to go fishing which he declines, Azazel adviced him to spend more time with his parents when he gets the chance. They arrive at a different dimension resembling a nighttime beach with two moons where they spot Ajuka next to Ravel who is in a bed barely conscious and assures them that Raiser was sent home safely by Slash Dog’s Team. Ajuka then explains to them about his secret creation from the general public known as the King Pieces and how some top-ranked Rating Game contestants have been using them, which was proposed by the higher-ups in the Underworld, a revelation that shocked everyone present. He then explains that while also having one in possession, Diehauser has only ever used his own strength, but reveals the champion's involvement in stealing Agreas in order to pursue the truth of everything, another shocking truth revealed to everyone. Soon Ajuka receives a startling call and tells them to return home as Ophis is being attacked by an Evil Dragon. Back at the Hyoudou Residence, where Ophis is unconscienced on her bed and brutally injured from protecting the Dragon egg from Niðhöggr, further to Issei’s horror, he finds out that his parents were kidnapped by him. Infuriated, he lashes out at Crom Craunch for not being there in time which Kiba attempts to calm him down. Kuroka and Le Fay came in from the rest of Vali's Team to bring info about the location of Agreas, the hideout for Qlippoth’s base. Later on, D×D prepares to strike back as they are teleported to Agreas, with the Gremory team being the main force. As Issei’s group make their way through Agreas to rescue his parents, they come across Niðhöggr, angered at the Dragon who injured Ophis and took his family, Issei activates his True Queen armor. Along with everyone else, they attack Niðhöggr with full force with Issei and Rias using their new technique that grants Rias her own variation of the Scale Mail armor; Crimson Extinct Dragonar. However, all their efforts are useless as Niðhöggr recovers from their attacks using several vials of Phoenix Tears, which is until Crom Crauch appears and brutally beats Niðhöggr, allowing Issei and Asia to head to where their parents are, with support from all the sword wielders to fend off against any Evil Dragons in their way.
While making their way through the designated building, Issei and Asia hear Diehauser on the monitor and he reveals to the public about the truth about the death of his cousin, Cleria Belia, for knowing the existence of the King Piece. They make it to where Diehauser and Rizevim are where Issei and the sudden arrival of Vali face them respectively but are overwhelmed by their power, things got more complicated when Rizevim brought Issei’s parents to witness their son in confusion, he then has Diehauser force Issei to drink Dragons blood, turning him more Dragon-like in front of his family who were in shock, especially when Rizevim reveals to them that Issei and his friends are not human. Rizevim mocks and laughs in ridicule towards Issei, calling him a monster in front of his family, he avoids eye contact as he cries and constantly apologizes to them, afraid that they might fear and abandon him. Instead, they still believe Issei to be their son and accept him as he is, standing up against Rizevim, Issei who is touched by his parents love for him is embraced by them and Asia.
While Issei unintentionally uses Pailingual on his mother’s breasts, he sees through his parents past which shows that they had difficulty giving birth, showing how happy they were when he was born, how worried they became when he was lost from them, as well as all the moments where they were there for him. Having regained the will to fight, he battles both Rizevim and Diehauser with his family supporting him; every time he’s knocked down he manages to stand back up, Rizevim attempts to kill his family but are protected by Asia’s awakened Balance Breaker which further irritates him. Issei starts hearing Ophis’ voice who then grants him and Ddraig power, achieving a new form; Diabolos Dragon (DxD), which proves to be immune to Rizevim’s ability and was able to cause him damage. Rizevim tries to heal himself with Pheonix Tears but is betrayed by Diehauser who renders it worthless. They fight outside in mid-air; all of Rizevim’s attacks are proven useless as Issei fires a powerful blast that nearly kills Rizevim, who is now greatly injured before he teleports away. Issei confronts Diehauser over his actions and is slapped by his mother for hurting her children, Issei tells him to atone for his sins as Rias and countless others including himself who want to compete against the Champion, Diehauser asks if Issei saw his cousin's soul while in Heaven, to which he replies that she had a gentle expression, an answer that brought him to tears. Issei starts feeling pain as he coughs blood and collapses on the floor with his family rushing over to him.
In Volume 21, Following his fight against Rizevim, Issei wakes up in the hospital one week later after his previous battle. Issei also loses his ability to speak and think about breasts without feeling pain due to the after-effects of using DxD mode, which he is warned to never use again. After recuperating enough, Issei saw his parents and met up with his friends to rejoin the battle against Qlippoth, with an army of different races preparing to face off against Apophis heading to the coastal waters of Japan with an impending army of Evil Dragons, Fake Red Dragon Emperor army and one of the Imperial Beasts bodies. After retrieving the stolen Holy Grail, Issei battles Apophis one-on-one in his True Queen armor within a black barrier and faces difficulty against his Umbrakinesis that dissolves everything it touches and avoids using his DxD mode. Issei lays on the ground injured and barely able to move with both his demonic energy and stamina exhausted, he notices the amulet his mother recently gave him fall off of his tattered uniform and inside he finds a photo of him with his parents when he was 3 years old and another of all the current residence at his home. While still in pain, this gives him the will to stand and fight as he begins to recite the forbidden chant.
Issei enters his Diabolos Dragon form and is finally able to inflict damage onto Apophis, as the battle rages on, the two clashes their strongest attacks with Apophis spewing his darkness breath which Issei's overpowers with his Infinity Blaster mixed Longinus Smasher, effectively killing him. Despite so Apophis' black barrier remained, however, a luminous horned-humanoid manages to enter, Issei and Ddraig realize that it's the consciousness of Trihexa. Sirzechs then teleports to their location, who had come to fight alongside Issei, they both give it their all to exterminate Trihexa's conscious which keeps on quickly regenerating. Ddraig notices Albion's revelation and decides to unseal his original finishing move for Issei to use; Blazing Inferno of Scorching Flames, an ability that allows him to spew flames of intense magnitude. However, Trihexa was still able to survive with Issei who changes back as a result of being unable to maintain his form any longer, collapsed onto the ground spewing blood. As the last resort, Sirzechs calls his entire peerage and reveals to Issei that they along with some of the other mythology leaders will be sealing Trihexa inside an Isolated Barrier Field along with themselves, Issei lays there shocked and in awe as he watches them disappear before his eyes and loses consciousness.
Issei wakes up again in a hospital, to his surprise seeing Ophis with a voluptuous figure, Vali who was also hospitalized explains that Ophis adjusted the borrowed power by stabilizing the infinite power within him to a level that his mind and body could withstand, effectively curing him of his Dragon Deficiency and resulting her current state and thus allowing him to see and speak about breasts without pain. Vali also tells Issei about the loss of Azazel, Sirzechs and the others, while he's upset at first, Ophis and Lilith comfort him by saying that they'll always stay with him. Vali also notes that both him and Issei are able to live for a very long time and will await Azazel's return to complain to him.
In Volume 22, Issei found himself lured into a room that has the same atmosphere as the Interdimensional Room, where he finds Akeno inside. Akeno began to seduce Issei by stripping his clothes and placing his right hand on her left breast. As Akeno is about to kiss Issei, they are caught by Rias in the act. As Rias is about to give her scolding, Akeno ignores her and gives Issei a deep kiss, much to Issei's shock. An enraged Rias gives her own deep kiss to Issei and begins to seduce Issei, and places his right hand also onto her own left breast. They were interrupted by the arrival of Ravel and the Church Trio. Ravel gives the news to Issei about the Rating Game World Tournament and Rias and Akeno give a cheek kiss to Issei as they leave to find out more about the tournament. During school, Issei meets a new student and the newest member of the Student Council, Ouryuu Nakiri, who has been wanting to meet Issei for a long time as he considers him to be his role model. Issei goes together with Rias and Ravel to the Kuoh Town's underground, where he meets Bova who is the third son of Tannin and the strongest amongst his children, much to Issei's shock. Bova asks Issei to accept him as his retainer, which he asked Bova if he wants to be his servant and Bova rejected the offer knowing he wants a group of females as servants. After school, Issei goes fishing together with the Occult Research Club, the Vali Team, and his parents. Issei and Vali went to find a fishing spot where they discussed the Rating Game World Tournament and Vali's promotion to an Ultimate-Class Devil. Before the day of his promotion, Issei shows Kunou around Kuoh Academy and introduces her to Sona and Saji.
On the day of his promotion ceremony to becoming a High-Class Devil, Issei goes together with the Occult Research Club, Rias's parents, and his parents to the Underworld. Upon arrival at the Maous' territory, Issei goes into the ceremonial hall and thinks back to his times as a Devil. Issei sees a woman who sings the Oppai Dragon song in an opera version, which leaves Issei and the others troubled except Zeoticus who is deeply moved by it. After becoming a High-Class Devil, Issei was visited by Riser and his mother Lady Phenex, who offered to trade Ravel as his first Bishop and Rias decided to trade Asia and Xenovia as his other Bishop, and his first Knight. Issei afterward meets a boy and his ally, to which Ajuka introduces the boy as Shiva, the God of Destruction and his ally Mahabali, the young prince of Asura, making Issei become quite taken aback. As the frightened Issei shake hands with Shiva and Mahabali, Shiva asks Issei if he is aiming for women or fame, which Issei answers that it is both. Earning Shiva's interest, Shiva asks Issei to join his army for a possible war against Indra, which leaves Issei and everyone greatly surprised. Mahabali then tells Issei that he and the other Asuras have already decided to join Shiva's side, and wants Issei to join them so Mahabali can fight alongside him. Issei noticed Mahabali's anger towards Indra as he shakes the ceremony room with his aura out of rage. Issei remained silent, which Shiva took it as his approval and happily pats his back. Shiva then tells Issei that the Rating Game will be named the Azazel Cup and the opponents he wishes to fight will be gathered there. Cao Cao shows up at the door who is amazed that Shiva would become fond of Issei and continues to grow every time. Cao Cao then informed Issei that he is also participating in the tournament.On the morning of the graduation day, Issei goes together with Rias and Akeno to Kuoh Academy, going to the Occult Research Club for one last time before they leave. After the graduation ceremony, Issei proposes to Rias to which she tearfully accepts. Irina reveals to Issei that she turned down to join Rias' team and happily accepted when Issei asked her to join him. Issei then informs Matsuda and Motohama about his relationship with Rias, where the news causes them to be depressed.
Red Dragon Emperor of the Blazing Truth × White Dragon Emperor of the Morning Star: The True Dragon(s) of the Kuoh Academy
Past mid-April, Issei, and Ravel arrived late to the Occult Research Club due to preparations for the tournament. In the opening ceremony of the Azazel Cup, Issei and his team arrived on Ryuuteimaru (which it has become a gigantic ship). Issei then gets greeted by his rivals with Rias proclaiming she won't lose to him, and Issei saying he won't hold back and defeat her. After ten days, Issei and his team receive bad ratings in the tournament. They were later joined by Le Fay, Kunou, and Lilith, and Issei asks if they are enjoying their school life which they agreed on. Issei then meets Akeno and Baraqiel before his match with him, Baraqiel asked Akeno who she will be cheering, she stated it will be Issei and hugged him. This caused Baraqiel to shed tears and proclaim he won't lose to Issei. Akeno then revealed her sorrowful side; wanting both Issei and Baraqiel to win and expressed her jealousy for Rias, for having a strong man who loves her. On the day of their match, Issei and Baraqiels team's arrived at the "Azazel Stadium" within the 'Fallen Angels', they played the game Object Break where the must break the most number of objects out of 13 scattered within the field. The Objects are revealed to be female statues (which Issei noted that looked similar to Akeno), as Issei and team went off into the field after going over Ravel's strategies.
An hour and a Half since Issei was exploring the western side of their territory with Bova when they heard that the Lightning Team had broken the first object but eventually were able to catch up. Issei soon came across Baraqiel who asked him how far he has gotten with Akeno, too embarrassed to say Baraqiel assumed they've done the unspeakable, even getting angry when he confirmed they have kissed and demanded that he'd take responsibility. Clad in lighting. Baraqiel charged directly towards Issei and engaged in combat all while testing his compatibility with her. Baraqiel released a single bolt of lightning towards the sky and then retreated, this was a signal to all three of his teammates to destroy the objects they had in hand near Issei which sealed him in a barrier. Ravel offered a solution to use Castling with his Rook; Rossweisse to swap place, while successful, Armaros who had planned to ambush Rossweisse was also teleported there and used his Anti-Magic on her.
Issei started to chant to enter his DxD form but for a maximum of 10 seconds, he used his wing cannons to annihilate half the field, resulting in breaking 4 Objects and retiring the enemies Rook and Bishop. Issei made his way to assist Xenovia and Irina location where they were fighting Baraqiel and two of his teammates, he soon came across several opponents until Bova arrived to stop them and let Issei proceed. When he arrived at their location, Issei then fought against Baraqiel in his Crimson armor again while explaining his relationship with as a way to agitate him to create openings to strike yet also told how he cares for her. Baraqiel responded his words that even so he has chosen Rias over her and has not considered her feelings, he grabbed Issei by the neck while weeping while telling him he should've split him and Akeno from the very begging and that she'd be happier with someone else, he then proceeded a punch that shattered his helmet. Issei then recalled all his past moments and the thought of Akeno being with someone other than him, he came to a conclusion and yelled out that he loved Akeno. Issei goes on asking Baraqiel to allow him to take responsibility, promising to always make her happy while proposing to her on the spot, this resolve had boosted Issei's power enough to defeat Baraqiel.
A few days later, Akeno clung close to Issei's side feeding him and was referring to him as "husband", this angered Rias as the two girls then argued over who would take Issei's virginity and carry his child first. Issei was then recalling when Ajuka had summoned him to his research facility after his match, he revealed he was able to communicate to Azazel and the others within the Isolated Barrier Field. Ajuka, Azazel and Sirzechs told Issei that they're establishing a secret intelligence bureau called ExE and they want Issei to be its intelligence officer, Issei wasn't sure of the position, he said he'll at least think about it. Later on, as Issei was watching the announcements for the upcoming matches, Elmenhilde had paid them a visit wanting to join their team.
In Volume 23, Issei and his team had just won another victory for their continuing winning streak, though some of them worry that things usually go wrong in situations like these and discuss possible countermeasures that could be used against or for them. Ravel then reminded Issei it was time for him to proceed with his work as a High-Class Devil. Issei and his classmates had already become third-year students, in-class Rossweisse announced the Ball Tournament coming up, with Xenovia declaring that she and her Student Council will not lose against the ORC members. After school, Issei and his peerage were doing the work as Devils at one of Azazel's labs underneath a cram school that had become Issei's office. When Asia had returned from one of her job requests, Ravel and Issei notice that Asia seemed a bit off, they hid in the storeroom and discussed that her problem may be that she's overwhelmed from being President of the ORC and must help ease her troubles. When they came out, all the girls present assumed that they've committed shameless acts within the workplace, Issei attempted to deny it while Ravel takes the thought of it into account. Elmenhilde came in to serve everyone but tripped nearly shattering the teacups until Xenovia caught them with her Excalibur Ruler.
Issei and his team set up a meeting with Dulio's team at the Hyoudou Residence VIP room, to get members of both parties acquainted with each other, though it was also used to gain an insight on their opponents. He met with some familiar and new faces, in particular with Mirana Shatarova whom Dulio hinted at having a huge bust size as a possible strategy to use against Issei when needed. Conflicted with himself, Ravel offers Issei hers breasts anytime to avoid being distracted by Mirana's. He also met with Kiyotora Shinra who was a relative of Tsubaki. Dulio's team supervisor; Rudiger Rosenkreutz arrived late to the meeting, he was able to notice that Asia had been having difficulty as a club president and advised her to open up to her friends, Ravel caught on that Rudiger was aware that Asia was a club president, exposing that he had been investigating the situation to such detail. That evening, Ravel came over to Issei's room to sleep with him in place of Rias and Akeno who was absent while excusing it as simply her role as his manager and grabbed her his hand to press against her breast. Ravel told him about the time they were caught leaving the storeroom when she answered to everyone that she would satisfy any and all of his impulsive requests, letting him know that he is her King and can do anything he wanted to her. Although their moment was interrupted when Asia also came to spend the night, Ravel attempted to explain her situation a was merely her duty when Xenovia and Irina had rushed towards Issei like ninjas. Everyone clung to Issei showing off their breasts to him and how they tried different methods in making them big, Ravel also explained that Devil's bust continues to grow even after maturing due to their Demonic energy.
Issei went to Ajuka's research facility to inform Azazel and the other of recent events, Issei also told him that he was feeling troubled with being a King and the tournament, Azazel believed that it was due to him never enjoying a battle as they were a life-threatening but assured him that the tournament was a purely a game and informed him to enjoy his youth. When Saji came over to Issei's home declaring that he won't lose to him when they face each other, Issei responded by inviting him and Vali to go fishing, ruining the former's moment. On their fishing trip, Issei conversed with the other two Dragon wielders about needing a reason for him to enjoy a fight. The trio then met with Vidar and Apollon who informed them they've joined Typhon's team and will not go easy on them when they face each other. They soon heard news about Rias current match and the reveal of her new Pawn, the three of them headed to the stadium she was in and watched the end of her match as she and her team easily overpowered an Ultimate-Class Devil's team. Two days later at their club room, Issei had Ravel to narrow the best options for new members for their team to stand a better chance, Ouryuu arrived as the best option but to everyone's surprise, Tiamat had also come by as the boy was under her care. She requested that Ddraig to return all her rare treasured items he had borrowed when he was alive, leaving the responsibility in finding them to Issei as his current host, they proposed a deal that Tiamat will allow Ouryuu to join them for as long as Issei wins the tournament and used his prized wish to grant him all of her items to return to her.
After a day of Devil work and a meeting with Ravel, Issei came to the large underground bath to cleanse himself, he washed before he could notice that Akeno had crept up behind to offer washing her "husband's" back for him. Things progressed as Akeno then offered to wash his front, as she prepared to take things even further, their moment was interrupted by Ophis, Lilith and Kunou who were playing in the bath. Issei met with Lint Sellzen in the living room who was waiting for Rias, he then came to learn from her about her relations with Freed Sellzen and Siegfried who all came from the same institute and were artificially created from the genes of Sigurd. Xenovia and Irina soon came down and spotted Issei and Lint chatting, the two became somewhat passionate over the young girl who referred to them as her senors and had come to be closely acquainted with each other and chatted before Rias would arrive. The next day Issei and his team were training in a large underground training space within the Gremory territory where he had a mock battle with Ouryuu. They were then discussing how Rudiger may be someone difficult to deal with, Roygun had arrived on Ruvel Phenex's advice to find a job, gave them the game date on Rudiger that could be helpful on their next fight. Roygun began to flirt with Issei which triggered a strong reaction from the girls present, Ravel got in the way as she recalled that Roygun was into younger men, though Issei felt a little excited over it. Roygun asks Issei if he wasn't interested in older women but answered that he was very much into them, his responses made the other girls him stinging gazes at him while Ravel continued to hold onto his arm to keep him from her. Roygun giggle as she watches the situation and then left saying she'll be rooting for them but also advice to enjoy the match no matter the outcome while giving Issei a wink.
On the day before their next match, Issei went back to Ajuka's research facility for a checked up on his Evil Pieces, he informed him that now all of them had become Mutation Pieces as an effect of his Dragon Deification. Ajuka concluded that the combination of the two could be described as a fearsome phenomenon and giving his form the power to change the world, while Issei currently cannot fully unleash it yet Ajuka can already foresee him being able to master it. He explained to Issei that if he can get Ophis and Lilith to resonate, used his pieces to unleash the power of Ophis and Great Red within himself, he will master Dragon Deification and achieve a new form known as AxA. Issei returned home as he found Asia practicing shooting hoops in secret for the school's tournament at their basement, she told him her discomfort that she feels lacking behind as the ORC President but still determined to improve herself for everyone in her own style different from Rias, Issei felt touched by this and joined her. Elmenhilde walked in on them wanting to also be of help in their training, upon overhearing Asia's conversation, she then gave a full detailed explanation for wanting to take part in the World Tournament, thus coming to an understanding. Though Issei questioned her why she wanted to join his team, Elmenhilde simply blushed while Asia scolded him for being oblivious. At that time, Xenovia and Irina had come down after their shower and decided to join them in a game of basketball, Asia then expressed how grateful she was to everyone. Ravel then quietly said to Issei that they'll use Elmenhilde for their match which Issei agreed.
On the day of the match, both teams arrived at the Ajuka Stadium in the Astaroth territory, Issei and Asia were surprised to see his father had also arrived alongside Kunou to cheer them on, though informs that his mother couldn't bear to see the fight directly instead will be will be watching the broadcast closely. When the two of them met with Dulio within the Stadium, he asked Issei if Asia would she be happier if she could live life as an ordinary sister, while Issei has thought so, Dulio pointed out that her current life with everyone that had been caused by the imperfection of Sacred Gears, the was same said for a few others he knows. They played the game under Rampage Ball rules, where they must find the goals that appear all over the game field and then throw the ball in. After going over last-minute strategies with Ravel, they made their way to the ball but were met with ice cold heavy rain and lightning strikes by Dulio, the ball was fought over back and forth but Issei's team were able to score the first 5 points thanks to Ouryuu.
As the game goes on, Dulio's team exploited the weaknesses of Issei's team under Rudiger's strategies, in his case he was trapped in a bubble that showed a recording of Gabriel chaining swimsuits completely mesmerized, though he was soon broken free by the combined attacks of Ouryuu and Bova. Ravel gave Issei the signal to used his Wyverns to create a new set of Scale Mail armor for Xenovia, he then only partially transformed his arm into DxD that send all the Angels who marked him to be sent flying by, which he used to enhance his Dress Break spell that halted Mirana's movements from a distance and stripped her of her clothes. Nearly 2 hours have passed since the game started with the scores of both parties being roughly even as everyone loses stamina. Xenovia told Issei of her trump that could boost her motivation depending on his answer, she proposed out loud that he'd take her as his bride, Irina also stepped in requesting the same. As Issei soon regains his composure, he accepted both their proposals and as if the fatigue of the two was blown away, they both gained a huge motivation as well as a massive power boost as unbelievable aura surged forth from their Holy Swords. The two swords-women fought their respected foes while also requesting the number of kids they wanted.
Issei and his team gained the last ball and headed over to the goal as Dulio's team chased after them while creating violent whether an attempt to blow them off the ground, Issei may have been tired and struggling but was still able to smile as he was finally able to enjoy a fight without the risk of lethal danger. All of the sudden, Issei hears a song inside him similar to the one Ophis and Lilith sang in the bath but now with Great Red as well. Issei's path was blocked by Dulio and the two fought with their attacks causing destruction to the field. While the ball was passed to Xenovia, Nero was able to take it and pass it to his comrades before the two of them collapsed, Issei used partial DxD only on his wing fly fast enough to snatch the ball and pass it to Rossweisse who then gave it to Bina. Just as she was about to score the winning goal, the timer went off ending the game with Dulio's team as the winners with a score of [144 – 146]. Everyone laid down on the ground tired, despite experiencing their first loss in the tournament, Issei expressed his joy in actually enjoying a fight for sport, Dulio dragged his tired body to his side and complimented him on coming in close and for all the secret techniques they pulled off. Later in the waiting room, Issei cheered up some of his teammates who were feeling down over their loss about learning from failure to improve, Issei then commented that he may have closer into achieving AxA some point during the match. Issei then took Ravel elsewhere private in the corridor for no one to see her express her sadness, he hugs her for a while to also lighten her up. Later on, Issei and some of his club members participated in the school's ball tournament in a game of basketball against Xenovia and her Student Council, he personally went up against Saji who treated it as a prelude to their upcoming match, in the end however the score was tied up. Issei walked home with Asia while the way they came across an injured boy whom Asia healed, somewhat reflecting how the two first met. Issei then made a resolve as he held Asia's shoulders and proposed to her which accepted in tears, just they were about to kiss, Xenovia and Irina sprung out from hiding after witnessing them and congratulated her as the three of them are now engaged to Issei.
While listening to the next upcoming matchups, Roygun and her peerage arrived at Issei's home pledging allegiance to Issei and his team, she explained her reason was to continue contributing to the Rating Games for she feels she has nothing if she doesn't compete.
In Volume 24, the Gremory group visited the school pool to relax while all of while most of the girls were fighting over who should Issei apply suntan oil to first. Rias declared to go first as the one who stripped her top before anyone, Xenovia took it further by attempting to continue the baby making practice in the storage room from last year while inviting all the members of their team to join but Rias and Akeno were against it, Xenovia then challenged Rias to a swimming contest to see who gets him. Issei then watched as everyone had fun until a topless Kuroka came from behind pressing her breasts covered in oil against his back, she then rubbed more oil all over him with her hands while licking his neck. Koneko came over to put a stop to and informed her to wait her turn like the others, though she still clung to Issei saying that she's being bullied. Issei then asked Kuroka to call him by his given name since they're living together which she takes into the suggestion, she then runs off when Ravel caught her cutting in line. Everyone then caught word that all their parents and guardians have met up at the Hyoudou Residence. Upon arriving home, Issei and everyone learned that they've all gathering was to discuss plans for the wedding ceremonies for each of his fiances, upon hearing this the girls made their requests to their parents, Kiba commented to him that there might be many VIP guests attending his wedding ceremonies and assured him that it's was normal to feel worried. Issei and his team were not only surprised that Vasco was also present but had also joined Rias' team for the tournament. His mother told him that they had to inform his grandmother but worried about how to explain the situation, his dad then brought up that his grandfather would've easily believed the existence of supernatural beings.
Issei went shopping with Ravel on the following day when they came across Bennia and Ouryuu who were looking for help as they and some of their friends where being attacked by Grim Reapers, they headed back to school to assist but as soon as he equipped his armor, the reapers immediately fled. They suspected that they worked for Thanatos and were after Koneko. That evening they brought this attention to Rias who heard a similar situation from Sairaorg with some unidentified Devils causing riots, they then received a message from Tobio who had relevant info on the topic. Issei, Rias, Ravel, and Rossweisse with Tobio at the bar he worked the next day, they also met with Lavinia who showed Issei an old notebook of Vali's that he had written cool and deep sounding phrases that Issei has to hear from Vali in person before. Cao Cao then appeared before then with the info Tobio called everyone for, they learned that there's a faction of Grim Reapers led acting behind the scenes of the tournament, the unidentified Devils were somehow confirmed to be pure blooded and Grim Reapers led by Hades were spotted during their riots as well as were unrelated to the ones that attacked Koneko. Back home at the VIP room, Ravel suggested that they needed to know more about Koneko's past to find out why she became a target, with Sona and Tsubaki's assistance they recommended visiting the mirror Youkai who can communicate with those who have parted. As everyone used their connections to find it, Rias reminded Issei of the branch house of Naberius that took in Koneko and Kuroka, informing him that they were obsessed with a certain dark research which against the main family’s wishes continued to carry out dubious experiments.
Rias invited Issei's team for a training session to help her for the upcoming match against Vali's team, Kiba offered a mock battle with Issei after his lunch but they were suddenly attacked by Grim Reapers. Equipping his armor, Issei and everyone fought against the Reapers and demanded to know what they wanted with Koneko but simply dodged the question, he then asked if Hades was behind this but answered no as they confirmed that they follow Thanatos instead. However the Reapers had no luck obtaining their objective with the late arrival of Vasco and Crom Crauch and their leader defeated, they resorted to retreating. Back home they had Bennia call her father to find additional info on Thanatos. Issei, Rias, Akeno, and Ravel transported to an old shrine that was situated deep in the mountains of the Tohoku region in Japan to meet with the mirror Youkai. While Sona introduced the current Ungaikyo, it stated that he cannot fulfill their request due to complications but was immediately persuaded when Magari also arrived who also wanted to know the details of Koneko's past. Although the Ungaikyo informed them that the soul of Koneko's father had been placed under seal, Magari had ever one prepare a tub that would allow her to negotiate with Great King Enma but still proved to be difficult as the seal was was done by a magician using demonic energy, she added that they could get some leeway when they get the cooperation of a Satan and a magician’s association. As Rias, Akeno, Ravel, Sona, and Shinra used their own respective channels to seek help, Magari brought up that he could use the Ungaikyo to call for someone else while he waited, Rias suggested he can call his late grandfather. Issei was happy to be able to speak with his grandpa again who had been living luxuriously in Buddhist Heaven due to Issei's many victories over the year, he also meets Rias and admired hers and Akeno's chest recalling Issei wanted to marry a "onee-san" with big breast when he was younger. Their communication was about to be cut off, he assured that should anything happen he will come over to help him and leaves his parting words to Issei to feel up as many breasts as he can.
With the cooperation of the other factions, the Ungaikyo was able to bypass the seal and summon the soul of Koneko and Kuroka's father but was having trouble remembering anything, although he slowly recalls his memories as they asked him questions. They learned that he had been experimenting on artificially creating Super Devils for the branch house of Naberius as well as someone of Nebiros which greatly shocked everyone, Issei got angry with him when he found out that he did not have mutual feelings for the Nekomata that fell for him or aware that the girls she birth were even his. Furthermore, they learned that one of Koneko's hair clip ornament that was a memento from her mother had the research data on his experiment, thus explaining why she was being targeted. As their line with him was about to be disconnected, the man begged to know if his research had been successful before being cut off. After returning home, they informed all their comrades everything they had discovered while omitting any mention of her parents to Koneko, she willingly gave her hair clip that was lent to Ajuka. Le Fay and Kuroka had just returned from the depths of China’s Youkai world, they soon informed Kuroka that her sister was being attacked by Grim Reapers and will also come after her, Rias then talked to her in private about what they uncovered about her parents. That night Issei came to see Kuroka who was on the roof aware that he already knew about their past, she requested that they not tell Koneko the truth. She opened up to him about her past on how bad a human their father was and how one-sided their mother's feelings were to him and tried to get him to acknowledge their children and when they had no choice but to be servants of the Naberius house after their parents died in a lab accident. Kuroka hugged Issei and expressed that she wanted to continue living with Koneko and everyone in peace, promising to make amends for all she had done and assist them against any threat they face, he held onto her assuring that he will always protect them as they are both his family.
Issei went down to the bath where he found a naked Koneko who handed him a shampoo bottle, they talked about the tournament where Koneko expressed that she must defeat Kuroka for Rias on their next match as the best way to completely gain closure from the fear, and loneliness that she felt back when Kuroka killed her previous master, Issei responded that he'll be cheering for them both, while Koneko was glad she hoped that he would cheer for her more then Kuroka. Koneko then admitted that she suspected that Issei was aware of the truth about her parents, she assured it was okay that he doesn't tell her for she was already happy with her current family especially with the one she loved, with that she reminded him of the proposal she made to him back during the Demonic Beast Riot and to give her an answer when she "grows bigger". Koneko stepped out of the bath knowing Rias was behind the entrance and gave her space alone with Issei. As Rias entered the bath with him, Issei also told her that he will be cheering for her, Rias winked as she undauntedly said not to hate her if she were to defeat his rival. They were about to kiss when the Church Trio had also come in and unintentionally interrupted the moment, Issei and Rias simply looked at each other and laugh. On the day of Rias and Vali's match, Issei and all their comrades acted as guards around the Fafnir Stadium within the Fallen Angels’ territory of the Underworld, against the Grim Reapers of Thanatos faction who were likely strike again. He meets for the other members of Tobio's Slash Dog team; Natsume Minagawa whose a fan of his show and Kouki Samejima who also claimed to love breasts. Issei and Ravel stood guard at the entrance while listening to the match going on, she then tugged his sleeve and pointed in the direction of Suzuka Himejima, he went over to meet with greeting her, he also recalled from Ouryuu that she was a scary person. Suzuka then introduced Seiryuu Kushihashi and Genbu Doumon were also the current heads of their respective clans, while the original came to cheer for Akeno, the three of them wanted to assist in guarding the match after asking Tobio. Suzuka then approached and whispered to Issei that she heard he had proposed to Akeno, he asked him to make her happy while recalling the trouble she went through by her predecessor, she smiles upon Issei giving a positive response. They then separated and he was back with Ravel, she determinedly said to him that she will defend her friend's important match, Issei likewise shared the same feelings.
When the Grim Reapers finally struck, as part of Ravel's plan Issei who equipped his crimson was located in a wilderness area at a far distance away from the stadium waiting for Thanatos to appear. Thanatos arrived via forced transfer against his will, Issei asked his reasons for doing this, he explained that he intended on destroying any and all research data on artificial Super Devils before Hades gets a hold on it, this included eliminating those connected to it such as Koneko and Kuroka, he also expressed interest at the chance of fighting the Red Dragon similar to his old comrade; Pluto who faced the White Dragon. Issei fired several Dragon Shots but Thanatos dodged them all at incredible speeds that left afterimages, even the ones he was able to land on appeared unaffected. Issei changed his attacks into melee while avoiding getting hit by his scythe that left large scar on the ground, although Thanatos was fast enough to avoid getting hit by his punches, little did he knew that the Grim Reaper had circled behind as he prepared to swing down his scythe, Issei managed to gain some distance when he fired his Crimson Blaster cannons in his wings. He brought out his Ascalon blade and activated his Penetrate, Thanatos immediately retreated backward as flew in closer from above and fired his cannons again, however, he missed again as he once more circled behind to strike another blow but Issei was able to block it with his blade in time. Having no other choice, Issei quipped himself with his incomplete Diabolos Dragon armor, Thanatos moved at high speed that created afterimages of himself from all directions that prepared to attack at once, Issei failed to repel them they were all able to hit him, luckily his armor appeared to be impervious to his scythe due to Ophis' power. As his countdown was nearly up, Issei attempted to finish his opponent off quickly with his cannons but Thanatos had sealed them during his last attack so he resorted to firing more consecutive enhanced Dragon Shot, Thanatos continued to outmaneuver them at high-speeds which left Issei to be cautious about where they impact to avoid hitting the barrier. His time was up as the DxD armor was lifted and reverted back into his crimson armor while low on stamina, while Thanatos acknowledged that Issei was able to fight on equal footing against gods but pointed out his glaring weakness of having a short amount of time to use his full power, the Reaper was then finally able to slash through Issei' armor with his scythe in the abdomen but yet had effect on his soul. Ddraig informed his partner that his soul was now unaffected even by techniques of a god-class being due to Ophis especially with the inclusion of Lilith by his side made the effect even more remarkable, he speculated that she wanted to make both Issei and Vali become Dragon God-class beings.
Just as Issei was still having a difficult time with his opponent, his grandfather's soul had appeared within his Sacred much to the shock of both him and Ddraig, he explained that he was able to come over with the help of the great Shaka and assist them. As the gems of the armor begin to shine due to the old man's overflowing vigor, he reminded his grandson of the times they played together plastic models of robots and spaceships where he made up breast related techniques and told Issei that Breasts can overpower anything if he loved them enough. Suddenly the tail of his armor began to stretch and move on it's towards Rossweisse and wrap around her breasts to suck out its energy to power up a wave cannon from his wings that were now locked on Thanatos, Ddraig was still being surprised confirmed that Issei's grandfather was the one in control of them. The aforementioned deity of the Buddhist mythology had also appeared to show gratitude for Issei's song that his grandfather plays that brought joy to those who've passed on. Thanatos had noticed the deity's presence and attempted to finish Issei quickly by was unable to due to the bright halo that had appeared behind Issei from the Great Shaka. With the energy of the deity and from Rossweisse's breast converted into Demonic energy within his cannons, Issei had just enough power for a wave cannon to defeat Thanatos, calling it Nyuutron Beam Cannon. Just as Issei fired, Thanatos tried to escape it but was stopped by Grayfia and took the full blast, the Reaper laid on the ground defeated praising Issei for the fight and ridiculing Hades.
All was said and done after Thanatos was imprisoned, but Issei was upset that Rossweisse's breasts had shrunken as a result, his grandfather assured that they'll return to normal before long. His grandpa also revealed that he install various features into his Sacred Gear, such as adjusting his Pailingual to be able to contact girls from afar. With this new ability; Pai-Phone, Issei used Ravel's breasts to call Koneko and Kuroka through theirs to inform them they were now safe from their adversary. Kuroka proposed a bet with her sister, that whoever wins their fight gets to be Issei's bride, Issei himself however interjected and proposed to take them both as his brides, Koneko immediately accepted it as well as Kuroka after she had conveyed her feelings for him thus becoming engaged to him. Issei and his friends made their way to view the remainder of Rias and Vali's Rating Game and observed all the remaining matchups, one of which between Koneko and Kuroka made a new bet that the winner would take the lead in getting the first night with Issei which greatly embarrassed the latter. Issei's grandfather then prepares to say goodbye, with his partings words to Issei being to realize his harem; to propose every cute girl he meets and accept it when they propose to him, he left calling his grandson the best "Oppai Dragon". They continued to watch the game until Rias was caught in a situation where she had no choice but to surrender, resulting in a victory for Vali's Team. Issei and his friends visited Rias in the medical room with whom the latter was ashamed that her loss was witnessed by everyone, Issei then held her hand and praised Rias for her accomplishments during the game. Kuroka soon pops out hugging Issei from behind, announcing that she is now one of his fiances as well. Koneko came towards Rias and requested permission to change her name back to "Shirone", Rias allowed it and hugged her as she was happy that Koneko had finally accepted herself. Kuroka was also happy when Rias when she allowed her to use the surname "Toujou" like her sister as well, though she also expressed interest in taking the name "Hyoudou". Issei then pondered on which name to address Koneko as she replied either was fine but shyly requested him to call her Shirone in public and during ceremonies. Ravel informed Issei that after closely watching his battles, especially his most recent fight to protect those dear to him has reawakened something in her heart she had forgotten. Bina then responded to Ravel that his latest fight was something that would be categorized as Kingship as the path that their King walks upon. Koneko then came over to Issei telling him to bend down a bit to her level, to which she then gave him her first kiss, Kuroka then pulled him towards her to also kiss him. Issei was pulled back and forth while being kissed by the two sisters as the rest of his fiances were also eager to kiss him, he became conflicted over his situation but then remembered his grandfather's last words to and regained his confidence to become a Harem King.
In Volume 25, Issei went to bathe together with Ophis, Lilith, and Kunou. After Ophis finish rinsing her back, she sat in front of Issei and told him to carry her on his back with Lilith and Kunou joining her to the bathtub. In the bathtub Kunou began to speak with Issei about how she wants her breast to be big as her mother’s and Issei started to have perverted thoughts of comparing her breasts to Yasaka’s large breast and wants to massage them, Kunou started to realize what he was thinking stood energetically told him to be ready when her breast gets bigger with Issei making a mischievous face told her they’re still too small causing Kunou to pounce on his face with Ophis and Lilith mimicking her to pounce on Issei as well. Issei and his team began to watch the tournament in Issei’s room and see Diehauser attaining another victory in his match and managed to win against God-class teams. They started to watch a special program called “New Faces Noticed in the Tournament” which shows a group of mysterious devils with Balberith and Verrine being one of them and saw them easily defeated ultimate-class devils and subdued god-class beings and their king is a high-class Grim Reaper from Olympus. They then watch a program called Unknown Sacred Gears featuring players with new Sacred Gears and Ravel pointing one who controls iron and electronic devices is a member of Ruval's team and Ruval also has a God from the Egyptian mythology who was known as the ancestor of the Phoenix, Bennu. Issei is later informed by Ravel that the Sacred Gear user is the king of Shooting Star team and they kept earning victories. Roygun shares information to the team about the numbers of Sacred Gears continues to increase, shocking Issei and the group and continued to share information about the research on Sacred Gears which has been done by the Seraphs and the Grigori has been able to clearly confirm that there are several species that have deviated from normal Sacred Gears. Issei and Ouryuu became astonished to learn from Roygun that Gasper got his Longinus certification, which Issei became impressed on how Roygun was able to get this info before it was announced by the Grigori and Heaven and later Issei turned his attention to Rossweisse, who was bothered due to her marriage meeting.
The next day Issei went to the University of Kuoh Academy after school and there he meets up with Rias and Akeno who wanted to introduce him as their boyfriend to their friends at college, shocking Issei for them informing about their engagement. Issei noticed Rias’s and Akeno’s college friend’s eyes are lifeless due to Akeno using magic on them so Issei wouldn’t get exposed to the public about his engagement to Rias and Akeno. Issei speaks to Akeno about the marriage between Rossweisse and Vidar is different from Rias and Riser engagement and his enemy this time is a god instead of a member of the Phenex clan, Akeno tells Issei he became more mature than before as became calm rather than charge recklessly to Asgard to take back Rossweisse. On the day of Rossweisse marriage interview, Issei and the group went to a Japanese restaurant in Tokyo and there they greet Göndul who apologize to Issei for being unable to reject the Norse higher-up’s idea about the marriage and he witnessed the argument between Rosswiesse and Göndul and was asked by Koneko why didn’t he do perverted things to Rossweisse, shocking Issei on how bold she became after that proposal and says he if he could do perverted things he would but his status as a high-class devil, Oppai Dragon, and his participation in the International tournament made him quite busy.
Issei participates the marriage interview as the master of Rossweisse and Göndul being the representative of her family. While waiting in the seiza, Vidar arrived together with his escorts with Issei noticing his escorts are giving a strict expression to him, Rossweisse, and Göndul and their nature are divine. Vidar orders Fulla, Hlin, Gná to leave things to him and Issei formally introduces as a high-class devil and the master of Rossweisse to Vidar and began to watch the conversation between his servant and the chief-god. After Rossweisse accidentally drinks Vidar’s beer, a drunken Rossweisse hugged Issei while also telling Vidar that she will become Issei’s wife because he is a promising Oppai Dragon and he is kind to her and the Underworld is more favorable than Valhalla. A Valkyrie named Brynhildr appears from the balcony and scolds Rossweisse for being weak towards alcohol and accidentally drinking Vidar’s beer instead of her own drink. Issei and Rossweisse get shocked by Vidar’s words of being engaged to Rossweisse and loudly screams. He gets pointed by Vidar’s finger and makes a bet with Rossweisse on the line for their upcoming match in the tournament with Issei telling Vidar that Rossweisse is his precious friend and servant and doesn’t plan to give her up to the Norse God. Issei and his team gather information of Team Leisure of the Kings such as Typhon, Vidar’s abilities and calling Midgardsormr to join the team, and Apollon’s abilities. Issei’s and Rias’s team gets called by Ajuka who offered to help them get stronger in a training space and informed Issei that someone from Hindu mythology wants him to consider and asked him if it’s from Shiva which Ajuka responses it’s from Indra, much to Issei and everyone’s surprise. Cao Cao appears at the VIP room to pick up Issei under Indra’s orders to bring him to the Ocean of Milk and departed with him.
Issei and Cao Cao appeared together at the Hindu mythology’s Ocean of Milk and there he was greeted by Indra, frightening Issei and enter his fighting stance while Issei returns his greeting. Indra gets amused by Issei frightening expression and welcomes him to the Ocean of Milk and urges him to sit on a chair. As Cao Cao prepares for the preparation, Issei speaks with Indra about the tournament and they’re times where he has fun with Indra express his envious that Issei’s next opponent is Typhon. Issei continues his conversation with Indra and god of war reveals that the God-class teams in the tournament have been withdrawing due to powerful devils and the Longinus users like the fight between Vali and Crom, and the fight between Rias in Balor form against a complete Fenrir. Indra adds that Issei who harbors the power of infinite is a threat to God-class beings and him capable of blowing away an unskilled god. After Cao Cao almost finishes his preparation, Issei was told to hold the head of the legendary turtle Kurma while Cao Cao holds the tail so the snake-like dragon can wrap around the turtle’s back and being pulled reciprocally between Issei and Cao Cao, and that made the turtle rotate sideways. After finishing it, Issei was given the miracle drug Amrita by Indra was told to drink it and drinking it Issei began to feel an incredible amount of pain everywhere in his body due to the effects of the drug with Ddraig feeling the same pain. After losing consciousness due to Amrita, in his subconscious, Issei meets one of the pillar gods of ExE (Evie × Etoulde) Chichigami who came to warn him that a malevolent being may appear in his world and he’ll need to gather the twelve Chosen Heavenly Breasts in order to defeat the malevolent being. Issei wakes up with Cao Cao looking after him telling him he’s been unconscious for one day and miraculously came back fast.
In the Hyoudou Residence, Issei returns to sleep only to find Rossweisse on his bed wearing a revealing lingerie and shyly asked if he’s gonna come to the bed and then Issei went to his bed and laid down. Issei was shocked about Rossweisse attempts to offer her virginity in order to break off her engagement and reveals to Issei that she doesn’t want to marry Vidar and wants to be on Issei’s side, asking him to snatch her away from the Norse chief-god. Issei reveals that he has no intention to give Rossweisse to Vidar and recalling on how he did with Euclid, hugging her telling her to believe in him. Realizing that their face was too close to each other Issei and Rossweisse backed away with their faces turning red but Rossweisse came close to Issei and gave her first kiss, much to Issei’s surprise. Before Issei and Rossweisse about to kiss again, they were interrupted when Kuroka barged into Issei’s room in order to perverted things with him after learning that Rias wasn’t coming to the residence. Koneko follows after Kuroka, apologizing to Issei for unable to stop her sister from ruining his moment with Rossweisse. Issei gets a nosebleed because Kuroka’s statement of his child will be in her belly and wants his child fast no matter what place it is and asks Issei to make a lot of children with her as she nibbles his ear. Koneko strips her outer garments and gets on top of Issei while he noted that she became bolder while Kuroka asked Rossweisse if she wants to have Issei’s child which she panicked and decided to sleep with Issei and the Nekomata sisters agrees as the four sleep with each other.
On the day of the match, Issei and his team arrived at Valhalla in Norse mythology and entered the Thor Stadium. Issei gets good lucks from Rias and her team, his Gorou, Kunou, and Ophis and Lilith who will appear to watch Issei’s match. As the team entered the center of the stadium, Issei received cheer from the spectators from the people in Valhalla which surprises Issei because he thought he would be disrespected due to him being the Oppai Dragon. Issei watches as Team Leisure of the Kings arrives at the stadium and Typhon cheerfully shouted that his opponent is a Heavenly Dragon, as well as exchanges, gazes with Vidar. As the match started Issei went together with Irina, Xenovia, Rossweisse, Ravel, and Ouryuu on the stairway to one of the floating islands of artificial Yggdrasil and transformed into his crimson armor and watches as Xenovia, Irina, and Ouryuu decided to take on Apollon and properly introduces themselves as members of Issei and became pleased with them. As he and the team continued to reach to the top, they were stopped by the goddess Artemis with Grayfia and Asia challenging her to a battle. After continuing to the half point, Issei and his remaining team members see Typhon at the floating island wondering who will be his opponent and see Vidar inviting him to a vast floating island to be his opponent as he travels there with Ravel and Rossweisse while leaving Roygun, Bova, and Elmenhilde to deal with Typhon.
After reaching the highest floating island with Ravel and Rossweisse, Issei was greeted by Vidar and his Valkyrie Squad who suggested if he wanted to reach for the top to win but that would be considered boring by the Norse chief-god and the spectators so he offered to face Issei one on one match while Ravel and Rossweisse deal with the Valkyrie Squad. Issei begins to chat Ddraig stating this time his opponent is a God and Ddraig expressing his interest of wanting to fight Typhon after the talk Issei starts to fight Vidar by attempting to punch him but it was stopped by Vidar’s mystical boots who deflected the Issei’s blow. Chanting into his DxD form Issei noticed his countdown changed from 10 to 88 countdown and sent Vidar’s kick back with his punches and threw him off balance and as he closed the distance between them Issei summoned Ascalon to appear from his left hand and attempting to slash Vidar but he dodged the attack and jumped back as he pulled away from Ascalon and then he summoned his Ascalon II. Issei continued to overwhelm Vidar with his DxD form and his two Ascalon attacks, completely pushing him back despite being a god with Vidar also commenting his countdown has increased with Issei believing the miracle drug Amrita must’ve had an effect on him which allowed him to stay in DxD form for eighty-eight minutes thus becoming curious what would happen if his countdown reaches zero. After hearing Brynhildr and the Valkyrie Squad screaming due to learning that Rossweisse kissed Issei, Vidar whispered to him that Brynhildr and the Valkyries are virgins shocking Issei and watch Ravel and Rosswiesse defeating Brynhildr, Helmwige, Ortlinde, Grimgerde, and Schwertleite with their strategy.As he continues his battle, Issei watches as Vidar summons Midgardsormr’s will through a magic circle to remind him of the pact they made and agrees to help him by becoming his Sacred Gear enveloped him in a silver dragon armor which he named Ragnarök Earth Berserk. Issei’s gets overwhelmed by Vidar’s incredible speed due to his armor and gets heavily injured by his signature move Fimbulvetr Shot that sends him crashing onto Yggdrasil. Typhon and Apollon arrived to assist Vidar in his fight against Issei as he complained that he can’t afford to lose otherwise Rossweisse would be forced to marry Vidar and noticed his countdown has the number 8, but Ddraig realizes what does the countdown mean as the countdown reaches zero. The gems on Issei’s armor began to glow in a deep crimson light and forming into a giant red dragon which revealed to be Ddraig himself, much to Issei’s and everyone’s shock. Issei realizes that he is still wearing his despite Ddraig being separated from him with Ddraig explaining that he still connected to him and Issei watches as Ddraig takes on Typhon and Apollon and pushed them back with his flames, Boost, and Penetrate abilities. Issei and Vidar decided to continue their fight and Issei screams to Rossweisse to give birth many of his children with Rossweisse loudly agree with Vidar became dumbfounded and burst into laughter revealing he never had any intention of marrying Rossweisse much to Issei’s surprise. They continue their battle and after a climactic clash of Issei's Infinity Blaster + Longinus Smasher and Fimbulvetr Shot combo which he eventually dodges, Vidar is finally defeated by a clever maneuver from Issei with Ascalon and Ascalon II and Issei and his team emerge victorious after Ddraig defeated Typhon. Issei and Rossweisse together looked at the artificial Yggdrasil with Rossweisse telling him with a shy expression to see the real version together with her and agrees while holding her hand. Issei and his team celebrate their victory at the Hyoudou Residence along with his rivals teams. Vali speaks to Issei about he aims to be the winner and Issei also aims to be the winner as well but he must settle things with Vali first which his rival agrees. Issei’s other rivals such as Sairaorg, Cao Cao, Dulio, Yuuto, Crom, Tobio, Saji, and Riser comes to him and expressing their interest of wanting to fight Issei. As gets surrounded by his rivals, the Church Trio pulls him away from them and lands on Akeno’s chest but gets pulled again to Kuroka’s chest with Koneko also trying to pull Issei too. Issei’s get hugged from behind by a drunk Rossweisse and gets sent flying to Rias’s breast and they give each other congratulations as well expressing their love for each other. The other girls tell Issei to show his love for them which he does and tells them that everyone is his bride.
Powers & Abilities
Demonic Power: Issei has all the powers and abilities common to Devils, including the power to cast spells. His demonic power was originally lower than a child's, unable to travel via magic circles but now he has sufficient power to do so. Through the use of Promotion, Issei can increase his demonic power. In Volume 14, Issei can summon Ryuuteimaru and in volume 25 Issei can use magic communication circles.
- Dragon Shot (魔力弾, Doragon Shotto): One of Issei's signature moves. Issei fires a beam of energy by concentrating his magical powers. This move is usually used in tandem with the Boosted Gear to increase its destructive powers. He has also developed a small scale Dragon Shot that is meant for knocking out humans while fending off the members of the Hero Faction who are humans. After his fight with Sirzechs, being inspired by the way he uses his Power of Destruction, Issei starts working on how to redirect his Dragon Shot by moving them in different directions, first using it in Volume 9 against Cao Cao and again in Volume 12 during his battle against Jabberwocky.
Dress Break (洋服崩壊, Doresu Bureiku): The second of Issei's signature moves which he uses mainly against females. This move allows Issei to "strip" women by first coming in contact with them, concentrating his demonic power, then snapping his fingers to activate one of two effects.
- Ver. B (Body): This move is used to "strip" women by destroying their clothes and/or armor.
- Ver. A (Astral): This move is used to "strip" women by destroying the effects of spells or abilities that have been used against them.
- Pailingual (乳語翻訳, Pairingaru): Issei's third signature move. Pailingual gives him the ability to talk to the breasts of all females. It is a helpful technique as it helps Issei learn his opponents' plans and strategies by asking their breasts; however, due to complaints from female members from other peerages, Rias banned Issei from using this technique in Rating Games. This move, however, has a weakness which was shown in the Rating Game between Sairaorg when his bishop Coriana Andrealphus started to strip in front of Issei and instead of telling him battle plans her breast told him what she was going to strip next thus hindering Pailingual.
- Pai-Phone: Is a variant of Pailingual, using women's breasts Issei is able to communicate through breasts to other women's breasts.
- Nyuutron Beam Cannon: Issei's fourth signature move. Nyuutron Beam Cannon gives Issei the ability to attach his Scale Mail's tail to a woman's breast and absorb their breast energy. This allows a powerful beam cannon to be fired as the result of breast energy being infused with Issei's demonic power. The color of his beam is pink in comparison of his previous abilities. The woman's bust size is displayed in his gauntlet's jewel and the number determines how powerful the beam will be. By using Rosswiesse's breast, which size is 96, he was able to launch an attack comparable with Infinity Blaster. It is very powerful, as it was able to defeat the strongest Grim Reaper, Thanatos.
Immense Strength: At the beginning of the series, Issei's strength was considered to be below average compared to others. After his training with Rias and the others in the mountain, Issei when using his Boosted Gear shows that he could go on a level with Riser's servant. After his training with Tannin, Issei's strength is further enhanced along with his daily training. His strength is further shown when he fought against Rizevim Lucifer, a Super Devil. It is also stated various times in the light novel that his power is equal to that of an Ultimate Class devil. Azazel also stated that out of the young devils that there is only one person who can fight Issei head on and that is the former strongest young devil, Sairaorg Bael, further displaying Issei's strength. After his daily training with Kiba, and with the assistance of Sun Wukong himself his strength further enhanced to the point that he can fight Apophis an Evil Dragon that achieved Heavenly Dragon class using his Diabolos Dragon God. In Volume 24, Issei was able to keep up with Thanatos who The Strongest Grim Reaper.
Master Hand-to-hand Combatant: Issei was originally unskilled in fighting but after the training with Koneko and Kiba, Issei manages to obtain basic hand-to-hand combat skills. After his training with Tannin, Issei becomes more skillful in combat, having to learn how to survive Tannin's assault. In fact, Issei's prowess in hand-to-hand combat is shown when he went toe-to-toe with Sairaorg Bael, a fellow master martial artist in a fist fight. After his daily training with Kiba and also with Sun Wukong his skills in martial arts greatly improves to the point that he can hold off on his own against Diehauser Belial and Rizevim Lucifer who are both also skilled in melee and hand to hand combats. In Volume 22, Issei in Cardinal Crimson Promotion is able to fight on par against Baraqiel who fusing it into punches and kicks with Holy Lightning. Issei can also combine boost power from Boosted Gear and dragon aura increases the power of his physical attacks.
Promotion: Being a Pawn, Issei can use promotion to temporarily gain the traits of a Queen, Rook, Knight or Bishop. In Volume 8, after Ajuka Beelzebub rewrote Issei's Evil Pieces, Issei can now use Promotion anytime and anywhere without the King's permission.
Flame Blaze: Following his training with Tannin, Issei learned how to use Dragon Flames through Boosted Gear. He first inhales an amount of air to fill his lungs, then uses his demonic powers to produce a small flame in within his stomach and use Boosted Gear's ability to enhance it. While the air mixed the enhanced fire within his stomach, he breathed out a large stream of dragon flames from his mouth toward his enemies. He's also shown to widen the range of his dragon flames that can engulf the whole sky as shown his battle against Cao Cao in Volume 12. Because of the training, Issei has also developed a high degree of resistance to fire attacks, so that only the most powerful flames, such as those of a Dragon or the Phenex Clan, can injure him.
Dragonification: After sacrificing his left arm, and having it transformed into that of a dragon's in Volume 2, Issei's left arm was immune to damage taken from touching Holy objects. In Volume 14, due to his new body being made from the Great Red's flesh Issei can now freely turn any part of his body into that of a Dragon, by concentrating his thoughts on the specified body part. He first demonstrates the technique by turning his right arm into that of a Dragon in order to combat three Magicians who were sent to attack Kuoh Academy. It is extremely powerful, as shown when he easily breaks through their defense magic and knocks one of them out with a single punch. Issei has also been able to grow Dragon wings from his back. Unfortunately, once the transformation occurs, he is unable to return it to human form, unless he gets the Dragon energy drained from the transformed body part by either Rias or Akeno.
Immense Durability: Issei was originally very weak and vulnerable, easily hurt by the simplest attack. Through the use of Promotion, he can increase his defense. After his training with Tannin, where he was forced to survive Tannin's continuous assault, Issei's durability greatly improves, along with his daily training further enhanced his durability to the point where his body could withstand continuous usage of the Boosted Gear which he couldn't do so in the beginning. In fact, Issei's durability has been proven several times against opponents like Sairaorg Bael, Cao Cao, Grendel, and many others. In Volume 22, Issei can endure Baraqiel holy lightning and continuing to fight despite the intense pain.
Immense Stamina: Issei originally possesses average stamina. After being reincarnated into a Devil along with his daily training with Rias, Issei obtains more stamina to use the Boosted Gear. Following his training with Tannin in the Underworld, Issei obtains, even more, stamina that he could use when in Balance Breaker. He eventually obtains enough stamina to activate his Scale Mail without a countdown. In Volume 23, he was able to keep fighting at his best throughout the whole two-hour Rampage Ball Rating Game.
Immense Speed: Through the use of Promotion, Issei can increase his speed. In his Balance Breaker state, he can use the booster to further increase his speed. In Volume 20, in his Diabolos Dragon form, he was able to appear in front of Rizevim before he can react.
Skilled Tactician: Although he is often outsmarted and considered an idiot, he is proven himself to be a slight skillful tactician. In Volume 9, he acts as a leader and a tactical fighter, where he uses his brain to fight properly the Hero-faction. Issei claims that his skills are not that enough, but Kiba mentioned that if it is not for his orders they couldn't fight and defend themselves from the sudden attacks of the Hero-faction.
Survival Skills: Because of his training under Tannin, Issei has developed survival skills.
Swordsmanship: While Issei is not proficient in wielding a sword like Kiba or Xenovia, he has learned the basics of swordsmanship from Kiba and his sword skills improve in their training sessions together.
Stealth: Issei has also learned how to mask his presence from people.
Flight: While Issei still lacks the ability to fly using his Devil wings, Issei being a former Dragon can fly using his Dragon wings.
EquipmentBoosted Gear (赤龍帝の籠手, Būsuteddo Gia): Issei's Sacred Gear and main weapon. The Boosted Gear is one of the 13 Longinus which holds the spirit of the Welsh Dragon, the Red Dragon Emperor, Ddraig, one of the Heavenly Dragons. It is said to have the power to kill a God when fully mastered. Boosted Gear takes the form of a red gauntlet on the wielder's left hand that has the ability to Boost the user's power every 10 seconds without limit, and its sub-ability can Transfer the multiplied power to a being or object, it can even be focused on certain parts of the user's body such as the eyes for enhanced vision. Later it gains the ability of Penetrate to bypass any defensive abilities (including Rizevim's Sacred Gear Canceler) that would otherwise prevent his attacks from landing, however, it does not negate the deactivation of Balance Breaker. Penetrate's effects can also be channeled through any part of the body, such as the eyes, making it capable of seeing through anything, even women's clothing.
- Boosted Gear: Scale Mail (赤龍帝の鎧, Būsuteddo Gia: Sukeiru Meiru): The Balance Breaker of Boosted Gear that creates a Red Dragon Armor and Issei's primary battle form. Issei first activated his imperfect version of Scale Mail in Volume 2 by making a pact with Ddraig by giving his left hand to the latter. During his first battle against Vali, Issei used a bracelet given to him by Azazel which allowed him to use the imperfect version of Scale Mail for less than 15 minutes. Issei completed his Balance Breaker during his fight against Kuroka, poking Rias' breast to trigger the evolution. From this point, Issei can Boost without the 10-second limit. At the back of his armor, there are two rocket boosters that give a temporary boost of speed and flight. After the activation of the Juggernaut Drive, Issei's Scale Mail gained a pair of retractable Dragon Wings with Pteranodon-like claws that he can use as arms.
- Boosted Gear: Juggernaut Drive (覇龍, Būsuteddo Gia: Jagānōto Doraivu): A form unique to the Boosted Gear and Divine Dividing. The Juggernaut Drive temporarily removes the seal placed on the Heavenly Dragons granting the user immense power. The Juggernaut Drive, however, causes the user to lose sanity while having their lives devoured by the power. Issei indirectly activates an incomplete version of this form when he thought Asia was killed by Shalba Beelzebub with the negative emotion overpowering him thus triggering the Juggernaut Drive. In this form, Issei's speed is greatly increased to the extent that it can be hard for one's sight to follow. This form is also capable of creating Dragon arms and blades from the gems of the armor. It contains a small cannon within the mouth of the helm that shoots out a laser beam.
- Longinus Smasher (ロンギヌス・スマッシャー Ronginusu Sumasshā): It's finishing that is the most powerful attack of the Boosted Gear. A launcher appears from the chest of the form that is capable of shooting a powerful energy beam of immense destructive power.
- Illegal Move Triaina (赤龍帝の三叉成駒, Irīgaru Mūbu Toriaina): The Illegal Move Triaina is a specialized technique used by Issei Hyoudou that changes his Scale Mail armor into three different forms based on the Evil Pieces system.
- Welsh Sonic Boost Knight (龍星の騎士, Werushu Sonikku Būsuto Naito): Triaina's Knight form. In this form, Issei possesses enormous speed that far surpasses Sairaorg's speed, but to make full use of it, Issei must shed his excess armor, causing it to become thin to the point where it has low defense, making him vulnerable to powerful attacks.
- Welsh Dragonic Rook (龍剛の戦車, Werushu Doragonikku Rūku): Triaina's Rook Form. In this form, Issei possesses a massive amount of power and defense but has a low body maneuvering speed because of the massive, thickened armor.
- Solid Impact (ソリッドインパクト, Soriddo Inpakuto): It's respected finishing move that delivers a punch that has its power and speed increased by nailing the percussion hammer located at his elbow.
- Welsh Blaster Bishop (龍牙の僧侶, Werushu Burasutā Bishoppu): Triaina's Bishop Form. In this form, Issei possesses an enormous amount of magical energy, which he applies it to the two cannons at the back of his armor.
- Dragon Blaster (ドラゴンブラスター Doragon Burasutā): It's respected finishing move that is a severely boosted equivalent of his Dragon Shot capable of leveling battlefields and briefly warp space-time. The drawbacks to this is the amount of time it takes to charge the cannons and stamina lost with each shot.
- Cardinal Crimson Promotion (真紅の赫龍帝, Kādinaru Kurimuzon Puromōshon): The Scale Mail's Queen Form that is achieved by gaining the "True Queen". This form changes the color of Issei's Scale Mail armor from red to crimson. Cardinal Crimson Promotion incorporates all three Evil Pieces traits, making it the most balanced and most powerful form of Issei's Scale Mail. In this form, Issei is capable of using enhanced versions of the Illegal Move Triaina's abilities. This form, however, is still unstable and requires mastering the three forms of Illegal Move Triaina to stabilize its powers. In Volume 22, it is revealed that Issei can enter True Queen without having to chant, and due to Diabolos Dragon God mode, its power has been increased.
- Solid Impact Booster: By morphing one of the armor's gauntlets into Welsh Dragonic Rook's, it allows it for an enhanced version of Solid Impact. It can also be used in tandem with Ascalon to deal further damage to Dragons.
- Crimson Blaster: An enhanced version of Welsh Blaster Bishop's "Dragon Blaster" that shoots a powerful beam from the wings of the armor.
- Dividing Wyvern Fairy (白龍皇の妖精達, Dibaidingu Waibān Fearī): Originally taking the form of Dividing Gear (白龍皇の籠手, Dibaidingu Gia), a white gauntlet on Issei's right hand which he obtained in his initial battle against Vali in Volume 4. Issei placed one of the jewels on Vali's armor to his, creating the Dividing Gear which allows him to use Albion's dividing powers. This ability, however, reduces Issei's lifespan and thus was banned by Azazel. In Volume 16, Issei is no longer able to use Dividing Gear after gaining a new ability that allows him to create small white Wyverns from the gems of his armor that can not only Divide but can also Reflect incoming attacks. Unlike the Dividing Gear, It only requires Issei's stamina rather than reducing his lifespan. In Volume 17, Issei manages to change the white Wyverns red at will where they are able to use Ddraig's powers of Boost, Transfer and Penetrate instead. After training with Rias, Issei manages to make use of the red Wyverns to attach themselves on Rias to create her own variation of the Boosted Gear Scale Mail armor called Crimson Extinct Dragonar (深紅の滅殺龍姫, Kurimuzon Ekusutinkuto Doragunā). Issei also made use of the red Wyverns to attach themselves on Xenovia to create her own variation of the Scale Mail armor called Crimson Destruction Dragonar.
- Longinus Smasher: In Volume 17, Issei gains access to this ability when the Red Wyverns used Boost on him while in this form. An ability initially available to Juggernaut Drive that from the chest appears a launcher that fires a powerful destructive beam. This, however, leaves a strong fatigue on Issei as it drains a lot of his stamina and depending on how one uses it, it can change the environment. Due to its immense power, this ability has a very long recharge period, lasting at least a month.
- Diabolos Dragon God (龍神化－『D×D』・G－, Diaborosu Doragon Goddo): This form is the result of Issei borrowing Ophis's power. The armor undergoes further change, as its color changes to be both crimson and black and adding a second set of wings. The power this form grant is so great that it overwhelms Rizevim Livan Lucifer's Sacred Gear Canceler, previously thought impossible. Boost has been changed to D∞D as Issei powers up in this form with the ∞ symbol emerging on all of the gems. According to Issei, he was able to use this form because his body was created with Ophis's power and Great Red's flesh. Even so, Issei can only sustain this form for a short period of time, followed by pain that makes death pale in comparison. After the battle against Apophis, Ophis adjusted DxD into DxD G, removing the infinity in it and dubbing the form Pseudo-Dragon Deification. The form can only be maintained for three minutes at most, with the time limit becoming shorter by attacking or defending to the point it can last only ten seconds. In Volume 23, Issei reveals the ability to perform a partial Pseudo-Dragon Deification on his left arm, allowing him to use his Dragon God Aura to a lesser extent with less stamina consumption. With this technique, Issei can combine his Dragon God aura into both Solid Impact Booster and Dragon Shot. In Volume 25, after drinking the miracle drug Amrita, Issei can maintain his Pseudo-DxD form for 88 minutes in combat.
- Infinity Blaster: A further enhanced version of Crimson Blaster, the wings contain cannons that shoot out a powerful blast of red and black aura that leaves even Rizevim injured to an extent that his body is almost fatally damaged. By using it, DxD G's time limit of three minutes is cut down to ten seconds.
- Longinus Smasher: The form is not only capable of this move, but the blast it shoots out has been enhanced with the power of infinity, delivering further damage. It can also be used in tandem with the Infinity Blaster, fusing the two blasts into an even more powerful attack.
- Blazing Inferno of Scorching Flames: An ability that was sealed by the God of the Bible which Issei managed to unlock upon using his DxD form for the second time in Volume 21. Issei releases a powerful breath of fire which can incinerate anything, flames that never go out once ignited as they continue to burn even after being reduced to ashes and can probably burn the soul until nothing remains. The only existences known to be immune to these flames are Albion, Ophis, and Great Red. Its area of effect can cover an entire island.
- Dress Break DxD: By using his Dragon God aura, Issei can increase his range that halts a female target’s movement, and by strengthening his left hand he can destroy their clothes without even touching them.
- Ddraig Summoning: Due to drinking the miracle drug Amrita, Issei gained the ability to summon Ddraig into battle after the  countdown on the right gauntlet reaches zero.
Ascalon II (アスカロンII, Asukaron II): The second version of Ascalon. A long sword that releases holy aura, but is more of a dragon sword rather than a Holy Sword. Issei keeps this sword within his right gauntlet that was free.
- "President Rias Gremory's virginity belongs to me!" (Volume 2, Life ∞ vs Power ∞)
- "Stupidity is fine! If I can't win with ability, I'll excel through stupidity!" (Volume 4, Life 5)
- "That's because we have to look if there is an Oppai in front of us!" (Volume 7, Life 2)
- "I'll never forgive anyone who makes our president cry!" (Season 2 New)
- (To Irina) "No way, no way in hell. I’ve invested my entire aptitude in magic for this. Would you have me develop a technique that allows me to see through women’s clothing instead? I made such a choice bearing my thoughts, worries and all. I shall...I shall destroy more women’s clothes and then...and then...and then someday, as I gain the ability to destroy them just by looking, I shall continue my fight!" (Season 2 New, Episode 3)
- (To Irina) "Lechery is my strength! Lechery is my justice!" (Season 2 New, Episode 3)
- (To Matsuda and Motohama in school) "Boobs are heavier than someone's life." (Season 2 New, Episode 4)
- Issei's birthday is on April 16.
- Issei's appearance is based on Kazuma Torisuna from s-CRY-ed because the author is a fan of the series.
- Issei is a fan of Dragon Ball (Drag-so Ball in the Anime and Manga).
- In the Light Novel, Issei's Dragon arm is depicted as a scaly Dragon arm that covers his entire left arm, while in the anime, his Dragon arm is replaced by the Boosted Gear.
- The manga depicts Issei's Dragon arm as a combination of both.
- Issei has a tokusatsu show in the Underworld called Breast Dragon Emperor Oppai Dragon (乳龍帝お, Chichiryūtei Oppai Doragon), which stars him as the main character named Issei Gremory and it is considerably popular among the children.
- Supposedly, one of Issei's power-ups was to involve sucking Rias' breasts. Unfortunately, that was already too much for Fujimi Shobo, so the author resorted to something else.
- In the short story "25(Twenty Five) at the Clubroom with Rias-buchou!", Issei was stated to have black hair; however, the anime and light novel illustrations portray him as having brown hair.
- According to the Magicians, Issei's strength is ranked in SS-Class.
- Issei's life force is currently unreadable due to his body being made from Great Red's flesh and Ophis' powers. At its lowest which is zero it represents "dream" or Great Red and at its highest which is infinite, it represents "infinity" or Ophis.
- His favorite food is cheesecake.
- Issei's name means "Sincere/Honest".
- His surname means "regular soldier" in reference to him being a Pawn, as pawns are considered as regular soldiers in chess analogy. So his full name means "Sincere or honest regular soldier".
- Issei shares the meaning of the series' title that refers to Great Red: "Dragon of Dragons" as he can be considered a mini Great Red, who the title mainly refers to.
- In addition, he along with Vali have made another meaning for the title that refers to themselves: "Diabolos (Devil) Dragon".
- Issei is the only man in existence to have seen Gabriel in a bikini, as well as the most beautiful women in all of Heaven who serves under her; in an old school swimsuit, transparent negligee, and athletic clothing.
- Issei's first ever meeting with Asia may have been foreshadowing to the relationship between Cleria Belial and Masaomi Yaegaki, as at first, Issei and Asia similarly to Cleria and Masaomi, were forbidden from seeing each other in the same town; Kuoh Town due to the Devil's side and Angel's side still at feuds with each other.
- Issei was originally envisioned with Kiba's character traits but later changed into a pervert because Ishibumi felt those character types "weak" to be the main character.
- Issei was originally going to be just a human who helps Asia.
- Despite not officially being a member of the Gremory clan yet, he is already considered one by the members (minus Rias) and their servants.
- Issei makes review videos for Oppai Dragon products while acting as the "Oppai Dragon" himself and uploads them to DeviTube. This caused the merchandises' sales to increase.
- According to Ophis's spawn Lilith, Issei smells like her, Ophis, and Great Red.
- According to Elmenhilde, Issei's blood tastes sweet, mellow, and rich, and is absolutely addictive.
- In Funimation dub, Issei’s nickname Oppai Dragon is Grabbin Dragon.
- Issei, in reality, is the third child, with those two miscarriages suffered by his mother, he is the only surviving child of his parents and he has two older siblings were never born.
- In Volume 25, Issei is very popular in Norse mythology as many people in Valhalla were cheering for him.