Akira Fudo learns from his best friend Ryo Asuka that demons will revive and reclaim the world from humans. With humans hopeless against this threat, Ryo suggests combining with a demon. With this, Akira becomes Devilman, a being with the power of demon but with a human heart.

Determined to protect his demon world from heavenly angels, demon Masatora Akutsu heads to earth in search of a charismatic human to rally his kin. Masquerading as a high schooler for his recruitment mission, he's captivated by the lovely Lily Amane. But he's in for a wild celestial surprise, because she's his archnemesis—an angel—and she's set on reforming his demonic ways!

A new guardian "angelus" uncovers a secret behind the Angelus System's bureaucracy that leads him to break its official rules about protecting humans.