Detective Seiichiro Watari is nearing retirement, but is still bothered by an unsolved case from seven years ago when the decomposed corpse of a female was found by a fisherman in the sea of Otaru. The body was never identified so the case was never solved. Three years after his retirement, Watari unexpectedly discovers a clue that may finally solve the case. However, at the same time, he learns he does not have long to live. Although he is no longer on the police force, he puts all his energy into reinvestigating the case, in a race to solve the mystery before he dies.