Kokushibo's birth name was Michikatsu Tsugikuni and the twin brother of Yoriichi Tsugikuni, deemed as the most powerful demon slayer ever. Upon awakening his demon slayer mark, Michikatsu feared ...

In doing so, Michikatsu became one of Muzan’s Twelve Kizuki and changed his name to Kokushibo, making him slowly descend into the dark path. He made it his mission to defeat Yoriichi ...