In order to advance to the finals of the Azazel Cup, Issei and his team undergo special training. Meanwhile, Rossweisse is being engaged to Vidar and Issei has to challenge him before he can propose to her.
Tropes in this volume include:
- Back for the Finale: Fafnir returns for the final volume of the series.
- Continuity Nod: The Engagement Challenge between Issei and Vidar over Rossweisse during the preliminary battles of the Azazel Cup is reminiscent of Issei's previous battle with Riser over Rias.
- Finger Poke of Doom: Ddraig casually flicks Apollo away from Issei after the former is summoned in battle.
- Grand Finale: Of the High School D×D light novel series.
- I Want My Beloved to Be Happy: Vidar wants Rossweisse and Issei to be happy together because the former's not honest with her feelings.