Familiars are considered a basic requirement for Devils. They could assist their masters in various tasks, be used for information gathering and relaying messages, as well as perform any other odd jobs that their masters could think of. Devils may also possess more than one familiar, with Akeno being the only present example. Familiars are shown to have different abilities depending on their species. For example, Asia's Dragon familiar acts as her personal bodyguard and Issei's familiar, Ryuuteimaru, acts as a mode of transportation. Devils may summon their familiars to them at any given time.
Duties[]
There do not appear to be any specific duties that familiars are supposed to perform, though Rias has stated they can be used to bring information or carry messages. Mostly, they have been shown performing janitorial work and odd jobs for their masters.
Known Familiars[]
Bat (?)
Normal Bat Form
The Human Form Rias' Familiar Takes
Rias summoning her Bat familiar.
1/5
The actual race is currently unknown.
?: Rias Gremory currently has one, but its name is not known at present. In Volume 8, Issei describes it as a bat the same color as Rias's crimson hair. In the anime, it is revealed to have been the woman (suggesting that the familiar is female) who gave Issei the flier with the contract seal to summon Rias when she resurrected him as a Devil.
Cat (?)
Koneko with Shiro
Kuroka's familiar passing through
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The actual race is currently unknown.
Shiro (シロ): Shiro is the familiar of Koneko Toujou. It has white fur and hazel eyes, matching its master's.
?: Kuroka's familiar also appears to be a cat but with black fur to match hers respectfully. In Volume 6, Kuroka used her familiar to lure Koneko to her.
Tiny Demon (?)
Akeno with her Tiny Demon familiar.
1/8
The actual race is currently unknown.
?: Akeno Himejima currently has one, but its name is not known at present. In Volume 8, it is described as a small Oni. In the anime, Issei calls it an imp.
The anime shows Akeno has multiple of these familiars.
Small Bird (?)
The actual race is currently unknown.
?: Yuuto Kiba's familiar. Its name has not been revealed at present, and it is the only one of the Occult Research Club's familiars not shown in the anime.
Bird (?)
1/2
The actual race is currently unknown.
?: Riser Phenex's familiar, appearing only in the anime, it is a red eagle like bird, most likely a Phoenix. Riser has shown that he is able to see distanced things through the eyes of his familiar.
Sprite Dragon
Rassei with his new master.
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A top-tier normal-class Dragon that can generate powerful blue lightning. According to the Familiar Master, a Sprite Dragon needs to be tamed as a child or else they will become uncontrollable as adults. A Sprite Dragon is considered as a top-breed familiar.
Rassei: Rassei is the familiar of Asia Argento. It has blue scales, and spits lightning.
It is the legendary ship Skíðblaðnir that was created by the tribe called Ívaldi who also created Thor's Mjölnir. Supposedly, very few of these ships were created. Skíðblaðnir is a living ship capable of flying through the air.
Ryuuteimaru: Issei Hyoudou's familiar given to him by Surtr Second in the Extra Life of Volume 13. It initially appears to be a small ship (starting at the size of a toy boat) that will continue to grow and evolve into different forms by using the aura and imagination of its master as its source. Despite its small size, it call still fly while carrying its master. It was stated that as it grows, Ryuuteimaru would be able to fill the role of transportation and eventually serve as a living, flying harem palace for Issei. However, it has evolved in a different direction, taking the form of Apocalypse AnswerArms.
Dog (?)
Is a legendary creature in Okinawan mythology.
Final Death Shisa: Xenovia Quarta’s familiar. A black Shisa the size of a dog who was previously one of the Four Invincible Generals in the Vortex Bunch organization, that became Xenovia's familiar. He is a being that is said to protect a household, but instead wanders around travelling. When defending someone, he is said to be a master of defense though his weaknesses is beautiful women.
Potential Familiars[]
Other races have been mentioned as being possible candidates for Familiars. These include:
Dragon Kings[]
Tiamat: Tiamat was mentioned in the side story "The Familiar's Requirements" by the Familiar Master as a candidate for a powerful familiar, although it is stated that no devil has successfully made a familiar contract with her.
Undines[]
Issei's imagined appearance of what an Undine may look like
Bitter Reality...
Wild Undine Appears!
Issei imagining what an Undine may look like in the manga.
2 Wild Undines appear!
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Undines are described as humanoids with blue sparkling hair and the body of a male martial artist. Undines are said to be a water-type Seirei (Holy Spirit).
Nine-Headed Hydra[]
A Nine-Headed Hydra as described by the Familiar Master in the light novels.
The Nine-Headed Hydra's greatest features are its deadly poison that even Devils fear, and its immortal body. The Familiar Master touts it as one of the most evil pets who would even kill its own master.
At least one of these creatures resides deep within the Pet Forest. Rias Gremory seemed to like the idea of it being Issei's familiar and suggested they find it.
Slimes[]
Rias and Akeno - The Slime Duo!
Slime as it appears in the Light Novel
Asia covered in Slime
Tentacles attacking the Gremory Girls
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Slime are green gelatinous lifeforms, without a particular shape or form, which resides inside the Familiar Forest, the most common ones are weak against flames. According to the Familiar Master, Satooji, there's a subspecies that dissolves clothing, building a symbiotic relationship with tentacle creatures, which are fond of the secretions of women, making it easier to hunt. Although, Slimes aren't hostile, people, women, in particular, hates them and makes them undesirable as familiars.
Slime-taro: A slime (mixed with tentacles), which Issei Hyoudou had named and planned on turning into his familiar, after it attacked the women of the Occult Research Club. It was then destroyed by Rias and the others before he could make an official pact with it.
Rainbow Slime (レインボ・ースライム, Reinbo Suraimu): A special slime that shines with seven colors, which moves around in an undulating motion. It's a rare slime that appears at a specific place and time, in which has seven attributes: fire, ice, wind, earth, thunder, light, and darkness, having resistance to those attributes too.
Black Slime (ブラック・ースライム, Burakku Suraimu): A special slime, same as the original, but could survive after being struck by Rassei’s blue-colored lightning.
How to Obtain[]
On the night of a full Moon, Devils will go to a special forest and, with the guidance of a Familiar Master, capture and bind a familiar they find suitable.