Unholy Dragon of the End

The dream must come to an end—that is Issei's final goal. This is the story leading up to that final encounter, and somewhere in between, he gets caught up in this huge mess between various mythological factions and manages to score himself a harem. Featuring an adorable Ophis, a yandere Gabriel, and a crabby Crom Cruach as a mentor. Some OOC characters. OP!Issei x Harem.