A millennium ago during the Heian Era, Muzan was turned into a demon during an experimental treatment trying to cure his terminal illness, and his goal since then was to live without the fear of death and become truly eternal.He plans to accomplish this in two ways: finding the Blue Spider Lily or creating more demons in hopes that one day, one would be able to conquer his weakness of sunlight.Muzan is a tall man with a lean muscular build along with an unnaturally pale skin complexion.