High School DxD BorN

Summer break begins at Kuoh Academy with Issei Hyoudou and the Occult Research Club facing the consequences of their recent battle against Vali and the Chaos Brigade. The fight exposed how much experience Rias Gremory's team still lacks, so Rias and Azazel take the group to the Underworld for an intensive training regimen.

Their preparation becomes increasingly urgent as their enemies continue gathering strength. The sudden arrival of Loki, the Evil God of Norse mythology, introduces another powerful threat just as the club is trying to mature into a more capable team. Issei and his companions must turn their training into practical strength before the growing opposition overwhelms them.