Following the events of Part II, Itsuki and the gang's "Rave" business is close to getting off the ground. Itsuki looks to Meryl Hathaway, a young girl often seen accompanying Kotoko, as a counter to the violence of the Umon-kai as he searches for a way to destroy them once and for all.
Unfairly saddled with crippling debt after the events of Part I, Itsuki Ninomae and the gang turn to fellow student and daughter of a crime lord Kotoko Teshigawara for help. An intertwined web of loyalties and desire awaits as Itsuki, Kotoko and the others fight for justice.