Ikuo Ryuuzaki and Danno Tatsuya were two young boys who were raised by their mentor, known as 'sensei', after becoming orphans. Tragedy struck when their mentor was brutally murdered, leading the boys to vow to find the culprits and hold the police officers accountable for their lack of action in the investigation.
Over the next 15 years, Ryuuzaki pursued a career in law enforcement and became a detective, whereas Tatsuya rose to power in the criminal world as a mob leader. Despite their contrasting paths, the two secretly united to climb the ranks of their respective fields with one shared objective - to exact revenge upon those who had wronged them.
