Muzan Kibutsuji (鬼き舞ぶ辻つじ 無む惨ざん, Kibutsuji Muzan) is the main antagonist of Demon Slayer: Kimetsu no Yaiba. He 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.