Muon Nerima rules the red light district. After observing Zenichi Bunkyou's combat skills during a fight with bodyguards, Nerima recruits him as a potential successor. To prove himself, Zenichi must wear an SCM device. Nerima offers Zenichi one million yen for each slave acquired through SCM duels. This arrangement binds Zenichi to Nerima's criminal enterprise, employing the SCM system for organized activities within the district.