Ishigaki

Ishigaki is a unit chief in the police investigation whose role is to weigh emerging leads against jurisdiction, evidence, and the practical demands of the case. He does not simply endorse his detectives’ instincts: he insists that suspicion must be tested, directs their work, and asks what a proposed identification can actually explain. As evidence accumulates, his caution helps turn scattered clues into a formal investigative effort involving Kyoichiro Kaga.

Identity and Introduction

Ishigaki appears in the investigation room as a senior officer working alongside Squad Leader Kobayashi. When Kobayashi clears his throat and exchanges a quick nod with Ishigaki, the small gesture establishes them as colleagues coordinating the room’s business rather than detectives acting independently. Later, Shuhei Matsumiya and Sakagami are called before their superior officers and stand at attention, placing Ishigaki within the chain of command that governs their assignments.

The evidence does not give Ishigaki a personal history or a private life outside police work. His characterization comes instead through decisions: he listens to a subordinate’s concern about the Shinkoiwa case, refuses to treat a gut feeling as authority to cross jurisdictional lines, and returns the team to the question that remains unanswered even after an identity appears to be established.

Managing Jurisdiction and Assignment

Matsumiya raises a concern about the distance involved in the Shinkoiwa case and the possibility that it relates to work elsewhere. Ishigaki answers that distance is a matter of interpretation and that they cannot interfere in another case on intuition alone. The precinct responsible for Shinkoiwa already has its own task force, so he will make a note of Matsumiya’s concern but assigns the detectives to investigate in Shiga instead. His decision separates a lead worth remembering from a basis for immediate intervention.

This is not a dismissal of the detectives’ judgment so much as a limit on what judgment can authorize. Ishigaki acknowledges the concern while keeping the investigation within its proper remit; he neither confirms the suspected connection nor lets the team pursue it without stronger grounds. The exchange defines his supervisory function as both receptive and restrictive.

Weighing Evidence and Opening the Investigation

When the handwriting analysis becomes available, investigators report that the annotations on the calendar in Mutsuo Koshikawa’s apartment and a handwritten note supplied by Kaga were written by the same person. The matching handwriting makes the notes important evidence rather than two unrelated scraps. Ishigaki is among the officers involved as the finding is brought before senior officials.

The decision that follows is institutional as well as evidentiary. After discussions with the Homicide section chief and the commissioner, the police decide to make an official request for assistance from Nihonbashi Police. Kaga is told that his station commander is processing the request and that he is now joining the investigation team. Ishigaki’s presence in the investigation room and his participation in the case’s developing lines of inquiry place him within the command structure that makes this expansion possible.

Ishigaki also receives updates through the team. Matsumiya reports that he has told Ishigaki the main direction of their investigation, making clear that the inquiry is being coordinated rather than pursued as a set of disconnected interviews. Later, when Matsumiya returns to the incident room, Ishigaki is there with Kobayashi. Kobayashi reacts first to the report and says that he thinks they have their man, but Ishigaki immediately qualifies the apparent breakthrough: even if Mutsuo Koshikawa, also known as Shunichi Watabe, was Kazutoshi Yokoyama, the team still has to determine why he was murdered. Identification answers who the victim was; it does not yet explain the crime.

Evidence, Identity, and the Unanswered Motive

The identity problem is complicated by the records attached to Koshikawa’s life. He had lived in the apartment for nine years without updating his residence certificate. The paperwork he submitted on moving to Tokyo listed Maebashi, in Gunma Prefecture, as his previous address, but investigators sent there found nothing about him. The address was most likely false, and the building’s loose management meant tenants had not been properly vetted. These gaps make formal records an unreliable guide to the person behind the name.

A separate line of evidence links Koshikawa to the man who had lived in Sendai as Shunichi Watabe. Fingerprint evidence on an old train timetable supports the conclusion that they were the same person; the number and placement of the prints indicate that Watabe, rather than Kaga’s mother, used the timetable most. The distinction matters because names and documents have been manipulated, while the physical traces on the object help establish who handled it. Ishigaki’s question about whether the identified man was Kazutoshi Yokoyama therefore leads naturally to another: what was his motive for concealing his identity, and why did someone kill him?

The police’s reconstruction of Tadao Asai’s supposed death shows how an identity could be fabricated. Tadao had arranged for another man’s fingerprints to be placed on his belongings and had the man grip the bag handle, intending that the corpse be taken for his own. Tadao explained that he had planned to die himself but, after the substitution became possible, hoped that the authorities would believe him dead, stop the debt collectors from pursuing him, and take his daughter into care. The newspaper account from thirty years earlier said that identification had rested on fingerprints from the luggage and visual identification by Tadao’s daughter; at the time, the police had no reason to investigate further. This history demonstrates why apparently settled records and identifications require renewed scrutiny in the present case.

Supervisory Role and Narrative Significance

Ishigaki’s conduct gives the investigation a recurring discipline: an intuition may be recorded, a handwriting match may justify a new team, and fingerprints may support a reconstructed identity, but each finding must be distinguished from the question it does not answer. He permits an official collaboration with Kaga when the case’s evidence warrants it, yet he resists letting a suspected connection to Shinkoiwa override the existing task force’s jurisdiction. His caution is not passive; it shapes where the detectives go and what they must establish next.

That method also frames the broader identity puzzle. Koshikawa’s unverified address, Watabe’s use of a different name, Yokoyama’s possible identity, and Tadao’s staged death all show how a person can be obscured by paperwork, aliases, and mistaken identification. Ishigaki’s insistence on moving from a proposed identity to the motive for murder keeps the case from mistaking a solution to one part of the puzzle for a solution to the whole.