In Taishō era Japan, a secret organization known as the "Demon Slayer Corps" has waged a war against demons for centuries. Demons are species whose primary diet is humans caused the death and suffer for million humans. Muzan Kibutsuji is the Demon King, the progenitor of all other demons in existence, and the leader of the Twelve Kizuki, an organization made up of the twelve strongest demons under his direct command.