Kosuge is the district in Katsushika Ward where Michiko Oshitani’s body was discovered in the apartment rented by Mutsuo Koshikawa. Its role in the investigation is defined by a tension between what the apartment established—a homicide and a missing tenant—and what it could not explain: why Michiko had been in that part of Tokyo.

The Apartment and the Discovery

A week after Michiko’s body was found, investigators told her family that the apartment was in Kosuge and that its tenant was Mutsuo Koshikawa. The discovery had begun with a resident on the floor below, who complained of liquid dripping from the ceiling. When the building manager received no answer at the apartment above, he used a duplicate key to enter and found Michiko’s body in a closet. She had been dead for more than two weeks.

The autopsy established that Michiko had been killed by pressure to the neck. With homicide all but certain, the local precinct organized a task force, and the Tokyo Metropolitan Police Department sent a homicide unit to assist. Koshikawa, the tenant investigators urgently wanted to question, had disappeared; other residents had not seen him for at least a week.

A Place Without an Explanation

Kosuge became a central investigative question because Michiko’s reason for coming to Tokyo appeared to be a visit to Hiromi Asai, yet the police could find no plausible motive for Hiromi to kill her and no connection between Hiromi and the Kosuge apartment. Investigators therefore considered whether Michiko had another reason to be in the capital, but her phone contacts revealed no other person who might account for the visit.

Some investigators suspected that Koshikawa might have brought Michiko to the apartment by force in order to assault and rob her. That theory did not resolve the location’s larger mystery: neighborhood inquiries had uncovered no prior violent incident involving Koshikawa, and investigators reasoned that if he had brought Michiko against her will, the encounter would likely have begun somewhere nearby. They were left asking what had brought her to that part of town in the first place. Ten days after the body’s discovery, the investigation was making little progress.

Narrative Significance

Kosuge functions as a point of convergence, not an explanation. The apartment links Michiko’s death to an absent tenant, but the apparent distance between that scene and her known purpose in Tokyo frustrates the investigators’ early account of events. The district thus marks the gap between identifying where a crime occurred and understanding why its victim was there.