Muzan is the Demon King, the first of his kind, and the progenitor of all other demons in existence. Muzan is also the leader of the Twelve Kizuki, an organization of the twelve strongest demons in existence that serve directly under him. His main goals are achieving immortality and being able to walk under the sun, and he does this in two ways: creating and turning humans into demons to see if they can archive the two, or finding the Lily Spider. He turned into a demon during an experiment.