Reiji Kikukawa is officially fired from active police duty for gross misconduct after numerous complaints but his strong sense of morality leads his superior to secretly dispatch him as an undercover agent to infiltrate the Sukiya-kai, a ruthless yakuza gang, and arrest its fourth-generation boss Shuho Todoroki. He is instructed in how to work undercover by Special Agent Kazumi Akagiri and sent to an illegal casino run by the Akogi-gumi, an arm of the Sukiya-kai. He intentionally gets caught cheating in order to meet the boss Masaya Hiura, a.k.a. "Crazy Papillon", who is impressed by his humor and exchanges vows of brotherhood with him, bringing him into the Sukiya-kai. Kazumi informs Reiji that he is sure that the Sukiya-kai makes its money from selling MDMA but he cannot connect the street dealers to the yakuza. Reiji asks Hiura if the Akogi-gumi is clean and Hiura explains that his father Masayoshii Ako says that "drugs are the root of all evil."<br>