Demons are creatures of the night who die in the sun or at muzan's hand. Muzan is their master and their maker and king, he's a cruel and evil being. All demons must eat humans to survive and get stronger, and the better demons are gathered in two groups, the Lower Moons and the Upper Moons. Muzan is often disappointed by them, because they fear the enemy: the demon slayers. Muzan hates kamado Tanjiro and the other slayers, and wants them all dead. He's evil and he is also very strict