Cartagra: Tsuki Gurui no Yamai Adult

The hero of this story is Takashiro Shugo. An ex-police officer that is now unemployed and freeloading at a brothel. From time to time he takes on detective work from his former superior. As the story starts off, a missing persons case is dumped onto him. The person he is supposed to find is Kohzuki Yura. A girl he had an intimate relationship with before being sent off to war. While all this is being played out, a series of brutal killings occur in the background. As they strike closer to home, Shugo is no longer able to turn a blind eye and is dragged into the spiraling web of events.
(Source: VNDB)