In the dark streets of Tokyo, things have slowly but surely begun following the law of jungle where the strong devour the weak. This was revealed to be because demons have been appearing taking over humans. A school girl named Miki Makimura is a self-proclaimed witch who is helped by her childhood friend Akira Fudo in her exploits. When one of her rituals gets interrupted by demons, Akira is horribly injured and with his consciousness fading, his body is hijacked by the demon hero Amon. Afterwards the demon tribes begin to move in for a turf war to control the world. With much of their activity, people with pure hearts and strong wills become Devilmen continuing to fight against the Demons until they are the only party is left standing.