Hiram, the strongest demon king in history and ruler of all demons, defies the Demon God's demands for sacrifices. This defiance leads to a fierce battle that leaves Hiram dead. Despite being the strongest, he could not overcome the truth of this world: Demons cannot defeat the Demon God. Five hundred years later, Hiram has finally reincarnated as a human. While humans are considered the weakest race, they actually have the highest potential for growth — and Hiram fully intends to take advantage of that fact.