Kusumi Takeshi (Tokui Yu), a male resident, is found strangled to death in one of the apartments. Satoshi Itomura (Takaya Kamikawa), who is there, notices that Kusumi is holding something like a transparent thread in his hand.　
Soon, a surprising fact about Kusumi surfaced. His fingerprints match those of a suspect in an unsolved robbery. Seven years ago, a robbery broke into a couple's home. The robber stole jewelry and fled, but the victim's wife, who had a chronic heart disease, suffered a seizure from shock and lost her life. had caused a situation. According to Amemiya Hiroshi (Nagai Univ.), a member of the Special Investigations Office who was in charge of the investigation at the time, the stolen goods were not sold and no strong suspects came to mind, and the case went into a labyrinth. It says.
Shocked by the progress of the investigation in an unexpected way, Amamiya remembers a young man. That person is Shun Miyahira (Yuki Tamaki) who currently works at a yakitori restaurant. In fact, during the incident seven years ago, Shun heard a scream while jogging and went to the victim's house to help, and got into a fight with the criminal and injured himself. That injury cost him a chance and forced him to give up his dream as a boxer.
Strangely enough, Kusumi was a regular customer at the yakitori restaurant where Shun works. When Shun learns from Amamiya that Kusumi was the robber, Shun shows a surprised expression, but he says that he forgot about the incident long ago...!?