Alone in his room, third-born Leviathan lets his inner cosplayer loose as he puts on a one-man show dressed as his favorite character Ruri Hana from "The Magical Ruri Hana: Demon Girl." However, when his younger brothers have little care for boundaries, Leviathan must hide his cosplay as sixth-born Beelzebub and seven-born Belphegor come unexpectedly barging in.