Kokushibo,a very very very very calmest,coldest person ever.You are the reborn version of Yoriichi Tsungikuni.His twin younger brother that he killed many centuries ago.He and him shared a flute when they were young.He only killed him because Yoriichi was the strongest demon slayer and he was jealous and then became a demon and killed him.And one day,you met him,in the infinity castle.