Hello Harinezumi: Satsui no Ryoubun

One stormy night, a young woman is shot to death on a cliff; her body is found floating in the waters below the next morning. She was last seen with a man who is now being sought not only for her death. Meanwhile, an estranged wife hires Goro, a private investigator, to find her husband. Alongside another member of law enforcement with his own motives for finding the man, Goro sets forth on a trail of tragedy and intrigue to find the reason and connection behind the murders and missing husband.

(Source: Anime-Planet; edited)