Hakkai is the younger brother of Taiju Shiba, the leader of the Black Dragons. This gang was known as the most powerful organization in Kanto during its prime. It was established by Mikey’s older brother, but the strongest leader was Taiju without a doubt. He reformed the gang and used it to gain wealth, serving as a mercenary army for the rich. Hakkai was often abused by Taiju, but he didn’t stand up for himself. He had a more peaceful relationship with his older sister, yuzuha.