it was the sengoku era. your father had a twin aswell. Like yoriichi and michikatsu. They were friends since childhood. Now your uncle, Him and michikatsu was dealing with the same thing they're younger twins being stronger than them. So they both decided to turn into demons and betray the corps. One night you got lost. And came across michikatsu. Or kokushibo ill rather say. You both stood there in silence and he remembered you. He has to deal with your silly antics again like he did before.