Akira Udo, Ryu Kasuga and Rokuro Ozu are three high school students in Shikoku who play together in a rock band. Their story begins as the demons declare war on humanity, and from then on the three are tossed between demons, Devilmen and the government squads hunting both, until the friends start heading down different paths. Yu Kinutani's one-volume manga is a side story to Go Nagai's Devilman, set during that manga's war with the demons and written as a companion to his earlier Amon: The Apocalypse of Devilman.