Lucifero, the reigning Devil King, abruptly announces that he plans to step down and must name an heir. One by one, the Devil King Cadets assemble and head to the human world to compete for the succession. Osamu, a direct descendant of the Devil King, wants nothing to do with it. He cares far more about his part-time shifts at a convenience store than about the fate of the world. Left with no real choice, he begins gathering Child, familiars born from human souls, yet his mind stays on his job, and he trails the other Cadets by several steps. A single-episode supernatural action ONA, it sets the contest for the throne against one heir's plain indifference.