koku vs Yoriichi

this is ds slayer the upper moon 1 demon Kokushibo and the demons slayer king that they call him Yoriichi Tsugikuni who are twin brothers Kokushibo was originally Michikatsu Tsugikuni Yoriichi's older twin brother and they were close as kids but all that changed when Michikatsu became a demon and others thought that he died at the age of 25 but he became Muzan's right hand man and Michikatsu/Kokushibo has always been so cold to the other upper moons and lower moons but Yoriichi survived with the demon slayer mark and Yoriichi became old after living a long life as the first sun breather