Devilman centers on Akira Fudo, a reserved and hesitant youth who ventures into the Himalayas for a climbing trip alongside his father. During the climb, an unforeseen disaster claims both their lives. Akira's corpse is discovered and taken over by the demon warrior Devilman, who adopts his fresh human guise to carry out a plan of sowing havoc on Earth, clearing the path for a demonic conquest.
Before fully launching his agenda, Devilman encounters Akira's childhood companion Miki Makimura and instantly develops affection for her. Determined to shield Miki and all of humanity, he confronts his former demonic allies. Demon Tribe chief Zennon seethes with fury over Devilman's treachery and swiftly dispatches the ex‑comrades to annihilate him. The remaining demons soon realize Miki"s value to Devilman, compelling him to defend both her and himself. Can the strength of love triumph over genuine malevolence?