Kaga

Kaga’s investigation turns on a difficult distinction: personal attachment may shape what he fears finding, but it does not excuse him from following the evidence. His inquiry into Hiromi Asai leads him to connect the vanished Mutsuo Koshikawa, the man known in Sendai as Shunichi Watabe, and the supposed death of Hiromi’s father, Tadao Asai. The result is a reconstruction of a false identity sustained for decades—and of the family secret that made it possible.

Identity and Investigative Approach

Kaga is a detective who works alongside Shuhei Matsumiya and the wider task force. His method is to revisit assumptions when the available evidence no longer supports them. The investigators initially concentrated on Seizo Naemura as the missing man connected to Hiromi and Michiko Oshitani, but testimony ruled Naemura out. Kaga then reframed the question around the direct connection between Hiromi and Watabe, seeking the simplest explanation that could account for the relationship and Watabe’s disappearance.

That willingness to reconsider the case also governs his handling of physical and documentary evidence. The investigation found that Mutsuo Koshikawa had lived in his Tokyo apartment for nine years without updating his residence certificate; the Maebashi address he had supplied proved unproductive and was likely false. The absence of personal effects from the apartment further obscured who he was. Rather than treat an assumed name or an old record as conclusive, Kaga’s inquiry tests identity against independent evidence.

Personal Stakes and Professional Restraint

Kaga does not pretend to be impartial in feeling. He admits that he does not want Hiromi Asai to become a suspect, but says that this is precisely why he has checked the evidence so carefully. While reviewing five thousand photographs, he hoped not to find her. The volume of the search and his stated reluctance reveal the cost of the investigation without making that reluctance a reason to stop it.

His restraint is also visible in what he tells Matsumiya. At first, Kaga said he was looking for the man in a sketch; he explains that it would not have been fair to Matsumiya and the other investigators to launch a personal inquiry into Hiromi under that pretext. His feelings are real, but so is his obligation to the case. When Matsumiya asks how the investigation is going, Kaga responds abruptly, a brief sign of pressure rather than a departure from that obligation.

Reconstructing the Hidden Identity

A key evidentiary turn comes from fingerprints. Prints recovered from Koshikawa’s apartment match prints associated with the timetable, providing objective proof that Koshikawa and the Sendai resident known as Shunichi Watabe were the same man. The number and placement of the prints indicate that Watabe, rather than Kaga’s mother, made the most use of the timetable. This helps shift the investigation away from an abstract connection and toward a concrete trail linking Watabe to Kaga’s family history.

Kaga then brings together the duration and isolation of Watabe’s connection with Hiromi. He reasons that Hiromi and Watabe had been connected for at least ten years, that Watabe had few other ties, and that Hiromi may have supported him financially. Given Watabe’s estimated age, his disappearance, and his acquaintance with Michiko, Kaga sees two plausible kinds of close relationship: a lover or a family member. He concludes that Watabe was probably Hiromi’s father, Tadao Asai.

The evidence surrounding Tadao’s reported death makes that conclusion possible but not yet certain. The account of his suicide appeared in the files of Biwa Gakuen Orphanage, without official records to corroborate it; Hiromi’s former classmates did not remember that her father had died. Kaga therefore questions whether the death occurred as reported and whether the dead man was Tadao at all. The Hokuriku Daily article supplies a further piece of the puzzle: the corpse had been identified through fingerprints on luggage and visual identification by Tadao’s daughter, a combination that had satisfied investigators thirty years earlier but could now be reconsidered in light of the other anomalies.

Testing the Hypothesis and Narrative Role

Kaga asks Hiromi questions face-to-face, and her reactions strengthen his belief that he has found the right explanation. He also obtains a sample of her hair for DNA testing against Mutsuo Koshikawa, also known as Shunichi Watabe. At the point described, the result is still pending; Kaga’s identification of Watabe as Tadao remains a hypothesis supported by a developing chain of circumstantial and forensic evidence, not a confirmed test result.

The reconstruction leads back to the original act of substitution. In the account of the past, Tadao tells Hiromi that he will fake his death by putting another man’s fingerprints on his belongings and having the man grip the bag’s handle. Hiromi is to identify the body as her father’s. Tadao says the deception will end the debt collectors’ pursuit and allow local authorities to take responsibility for her, even if she is placed in an orphanage. Kaga’s present-day investigation uncovers the lasting consequences of that decision: a false death, an assumed identity, and a secret that father and daughter carried for years. His decisive role is not simply to name the missing man, but to expose how apparently separate records and relationships preserve the outline of a life deliberately erased.