In a seemingly ordinary empty house, the body of a young woman is found in a hidden suitcase.This tragic discovery shocked the local community and attracted the attention of forensic doctor Mikoto.After a preliminary inspection, Mikoto found that the deceased's mouth actually had the same “red goldfish” mark as the victim in the previous two cases.This discovery makes it seem that there is some mysterious connection between these three seemingly unrelated cases.

Experts from UDI (Unnatural Cause Institute) quickly intervened in the investigation and suspected that this was a serial murder case committed by the same murderer.However, due to the lack of formal evidence, the police have always had reservations about the case and have not paid sufficient attention to it.Faced with the indifference of the police, Mikoto and her colleagues at UDI decided to personally dissect the newly discovered remains to thoroughly find out the cause of death.

During the autopsy, Mikoto discovered that the contents of the deceased's stomach emitted a strong rancid smell. This discovery seemed to imply that the deceased had suffered great pain during his lifetime.UDI experts conducted in-depth analysis and discussions on this matter, trying to find clues to solve the case.

At the same time, Kamikura had serious doubts in his heart after accidentally seeing reports about UDI.He decided to visit the police station in person, hoping to provide more help in the investigation of this case.However, at the police station, Kamikura unexpectedly discovered something even more surprising - the police seemed to have concealed some key evidence, which may be closely related to the truth of the case.

As the investigation deepened, UDI experts gradually revealed the truth about this serial murder case.They discovered that the murderer used a special drug to put the victims into a coma, then brutally killed them, leaving a mark of “red goldfish” in their mouths as a mark.The discovery shocked everyone and prompted the police to re-examine the case.