Muzan Kibutsuji, preferably Muzan, is the King of Demons and is the Leader of the Twelve Kizuki, a group of 12 exceptionally strong demons formed into a group and given blood from Muzan to make them stronger. There are Uppermoons, and Lowermoons, though all the Lower moons are deceased.

Muzan is the most powerful demon, and the first ever person to become a demon, which was over a millennium ago. He is a manipulative gentlemen, as he hides how manipulative he truly is with his looks.