Furachi na Keiji-san

Furachi na Keiji-san manga summary: A detective, Takeda Issei, for the sake of destroying a yakuza group, surrenders his body to a yakuza member, Ishii Suguru, in order to obtain insider information. Even though Takeda has a rule where "I refuse to have a lover or a special person," the reason Ishii becomes his lover is――.