Without a live host, demons cannot take shape. However, if a person's will is strong enough, they may defeat the demon and take its power for themselves, becoming a Devilman. Akira Fudou, despite his frailty and humble demeanor, has always had a bleeding heart. So when his childhood buddy Ryou Asuka asks for his assistance in locating devils, Akira gladly accepts. To Akira's amazement, the destination is Sabbath: an immoral festival of immorality and degeneracy. In the middle of carnage and death, demons possess the revelers, transforming their bodies into horrific monsters and causing devastation. In an impulsive attempt to save his closest friend, Akira unintentionally fuses with the devil Amon and becomes a Devilman, earning the ability to battle the other demons.