Lucifer of the Optional Attendance is the twenty first novel of the High School DxD series. It is the ninth and final novel of the Legend of Oppai Dragon and his Lively Companions arc.
- Encounter. White Dragon and Black Angel
- Life.1 Amidst the Feast of the Imperial Beast/Trihexa
- Life. Ba’al Lion of the Great King —Great King—
- Life.2 Team [DxD] Attacks!
- Life. Lucifer Dawn of the Morning Star/Lucifer — Death Match —
- Last. DxD Crimson (深紅) and Crimson (真紅) — United Front —
- Eternal Life. Amidst the White Snow
- Farewell Temporary
- Y Ddraig Goch & Albion Gwiber
- The remaining hopes
- Vali is the third male character to appear on the light novel cover after Issei on Vol 1 and Gasper on Vol 16.