Brutal: Satsujin Keisatsukan no Kokuhaku

Synopsis

Handsome, successful, and talented, detective Hiroki Dan has it all. Each investigation solved is another good deed to add to his pile of closed cases. However, while his work is fulfilling, there are still times when he becomes frustrated; the police are helpless when vile people are beyond the reach of the law. It is for this very reason that Hiroki takes matters into his own hands. An eye for an eye and a tooth for a tooth, Hiroki exacts twisted justice on the dredges of society, one "good deed" at a time. (Source: MyAnimeList)