Katsushika Ward is the Tokyo district where the investigation into Michiko Oshitani’s death converges on the vanished tenant Mutsuo Koshikawa. A first-floor resident’s complaint led to the discovery of Oshitani’s body in a rented apartment there; the search for the tenant then exposed a near-total absence of reliable personal records, making the ward a crucial point in the novel’s reconstruction of hidden identities.

Setting and Identification

When investigators asked Oshitani’s relatives whether they knew the name Koshikawa or had any connection to Kosuge or Katsushika, the couple could offer none. Kobayashi then explained that Oshitani’s body had been found in an apartment in Kosuge, within Katsushika Ward, and that Koshikawa was its tenant. The district entered the investigation not as a place associated with the victim’s known life, but as the location of an unexplained death and a missing resident.

The Apartment Discovery

Oshitani’s body was discovered on March 30, after a resident on the building’s first floor complained that liquid was dripping through the ceiling. The manager went to the apartment above, received no answer, and entered with a duplicate key. He found Oshitani’s body in a closet. Investigators determined that she had died more than two weeks earlier, and the circumstances indicated homicide.

The apartment also complicated identification of both the victim and the person who had rented it. Although a handbag and travel pack were found near Oshitani, they contained no useful identifying documents. Koshikawa had disappeared, and the apartment held no phone, photographs, identity cards, credit cards, or letters that could establish who he was or where he had gone. Investigators considered that he, or someone else, had deliberately removed the personal effects.

A False Trail and a Hidden Identity

Koshikawa had lived in the apartment for nine years without updating his residence-certificate details. His Tokyo rental paperwork named Maebashi, in Gunma Prefecture, as his previous address, but investigators could find no trace of him there and suspected the information was false. The building’s loose management had allowed a tenant to remain without proper scrutiny, leaving the address and the name on the lease as poor guides to his identity.

The investigation eventually established through fingerprints that Koshikawa was the same man who had lived in Sendai under the name Shunichi Watabe. Evidence from a train timetable found in the apartment also indicated that Watabe, rather than Kaga’s mother, had handled it most often. Katsushika therefore marks a decisive junction between the anonymous tenant and the other identity under which he had lived.

Narrative Significance

The ward’s importance lies in the contrast between an ordinary rental address and the extensive concealment it sheltered. In the apartment, the absence of everyday traces—documents, photographs, correspondence—was itself significant: investigators had to reconstruct identity from forensic evidence and records elsewhere. Katsushika is thus more than the setting of a discovery; it is the place where the murder inquiry begins to uncover a long-hidden connection between names, residence, and personal history.