Baji is your big brother, you are his younger brother ( you are a boy in this au )

Baji is in a Gang named Tokyo manji gang ( Toman ) baji is the Leader of 1st Division, he has jet black medium long hair and 2 sharp pointy teeth in the front

As Baji was watching TV while arguing with you in between, you said something which made Baji angry "i m not your brother, eh?"