In this world, man-eating demons prey on humanity as if people were livestock. The Godslayer stands against them, and every demon he encounters fears him. But this very power draws Muzan Kibutsuji's attention. He sets a trap and sends six Upper Ranks to attack the Godslayer, hoping to gain a powerful subordinate by turning him into a demon.
The Godslayer's heart fills with resentment as he resists the invasion of the demon blood. At the final battle in the Infinity Castle, he accepts the demon blood and becomes a new Demon King to fight against the demons.
