The Tokyo Metropolitan Murders pertain to a series of unresolved homicides involving ten individuals that transpired between 1968 and 1974 in the Greater Tokyo Area of Japan.

During the period from 1968 to 1974, a disturbing pattern of murders and assaults primarily targeting female victims emerged in the metropolitan regions of Chiba, Saitama, and Tokyo.

The perpetrator's method involved attacking and sexually assaulting women who lived alone, committing these acts at midnight, and subsequently incinerating their remains. The majority of the victims were in their twenties, and the suspect is believed to have a blood type of O−. In total, nine cases were documented, alongside two additional cases involving a suspect who was convicted but later exonerated, with connections to the series suggested by the similarities to the other offenses.

On September 12, 1974, a 37-year-old construction worker named Etsuo Ono was apprehended in Kitaura (currently part of Namegata) on suspicion of theft. He was transported to a police station in Matsudo, Chiba Prefecture, where he faced intense interrogation regarding his potential involvement in the murders, given his questionable history.