Kokushibo, formerly known as Michikatsu Tsugikuni, is the Upper Moon One of the Twelve Kizuki and the twin brother of Yoriichi Tsugikuni, the strongest Demon Slayer in history. Originally a skilled samurai and Demon Slayer, he developed Moon Breathing as a derivative of his brother’s Sun Breathing but was consumed by jealousy over Yoriichi’s natural talent. Fearing aging and death, he accepted Muzan Kibutsuji’s offer to become a demon, gaining immense power, near-immortality. Over 200+ age