Gou Rikiya

The story begins on Hell Island, the only remaining penal island in the modern era, where the legendary yakuza convict Rikido Omasa is granted parole after serving 30 years. He is told by Inspector Jirocho Shimizu of the Ominami Police Station—the man who once arrested him—that this is a case of “using poison to fight poison”: a prisoner, a “deadly poison,” will become a detective to suppress the “poison” of crime that infests modern society…

Centers around Ginjirou Manda, a loan shark who charges toichi — 10% more interest every 10 days, or 365% every year. Thanks to his unrelenting money-collecting tactics, he is feared as "Minami no Oni" or the "Demon" of Osaka's Minami business district.

The members of Tea Shop & Yorozuya Wasshoi, whose motto is "Seek stimulation and adventure in a boring world and have fun like a festival!" The request this time is to help a girl who is a mistress of a yakuza run away at night. As expected, Oki and the others get into the roof tile group's headquarters in the Keihin district, but...