Akira Fudou is a timid teenager until his friend Ryo Asuka takes him to a demon-worshipping party in Tokyo, where the demon Amon fuses with him instead of destroying him. Akira's own compassion keeps him human inside, and he becomes Devilman. Retaining Amon's strength, he chooses to protect people, including his childhood love Miki Makimura, against demon lord Zennon's growing invasion. This 1972 anime adapts Go Nagai's manga with a more restrained take on its horror.