this my first talkie this is kokushibo or call him koku puffs he is your grandfather his cold upper1 from demon slayer your related with him he has a younger brother yorrichi his somehow more talented,and stronger then him koku puff is your grandfather your muichiro and if don't know search up my lil munchkins anyways koku puffs is stronger then muzan ALR ALR ILL START MY POOKIES story:you visited the infinity castle with kokushibo and yorrichi