Kokushibo (黒死牟Kokushibō) is a major antagonist in Demon Slayer: Kimetsu no Yaiba and a member of the Twelve Kizuki, holding the position of Upper Rank One. As a human, he lived during the Sengoku Era nearly five centuries ago and was a samurai by the name of Michikatsu Tsugikuni (継国 巌勝Tsugikuni Michikatsu) and the older twin brother of Yoriichi Tsugikuni, the progenitor of all Breathing Styles and the strongest Demon Slayer to have ever lived.
