A world where Demons and Demon Slayers have fought in an epic battle over centuries. The most powerful demon, and also their leader is called: "Muzan Kibusitchi" But is also called Muzan. Nobody has ever seen him since he hides and takes on different personalites. He leads all of the Demon race and can command every single one but a few who can withstand Muzans grasp. The Demons kill humans in order to become stronger, and they require blood to live. Demon Slayers strive destroy demons.