Arai, Sekine and Shima's tape

The tapes become a turning point in the investigation not because they offer a clear confession, but because they preserve fragments of a conversation that point toward what happened to the dead and to the evidence left behind. Their journey—from a claim passed through a bar regular, to a quiet approach to Arai, to audio delivered through Sekiguchi’s yakuza network—shows both the promise and the limits of information moving through sources who could not safely speak openly.

Discovery and Leverage

Kimiko told Jake Adelstein that Arai had bragged about possessing tapes to a yakuza acquaintance who regularly visited her bar. In the account the acquaintance passed on, Arai believed the recordings made him safe: he had material on Sekine, including what was described as Sekine’s admission to the murders, and would not meet the same fate as Endo. This was hearsay about what the tapes contained, not yet a direct examination of the recordings. The distinction matters. At first, the tapes existed for the investigation as both a possible source of evidence and a claim Arai was using to protect himself.

The report put Sekiguchi in a dangerous position. If he took the information to Takada, Takada might find Arai, force the tapes from him, and kill both Arai and Sekine. Suspicion that Sekine had killed Endo was one thing; the prospect of an admission on tape raised the stakes. Sekiguchi instead brought the information to Takada’s second-in-command, whom Jake Adelstein calls the Consigliere. The Consigliere promised to handle it quietly, and found Arai without mentioning the recordings to Takada. Arai then became willing to talk. The account does not establish why he changed course, but the discreet approach brought information into the investigation without immediately exposing the tapes to Takada.

From Conversation to Investigation

Arai’s revelations redirected attention. He had not participated in the disappearance of the last four victims, but said he had learned from Shima, his driver, that Sekine killed Endo and his driver, Wakui, with poison and that Shima helped bury them. That account made Shima central: what Shima knew could implicate Sekine. Police arrested Arai on a fraud charge, not because they expected the arrest itself to resolve the old murder, but because they wanted information about Shima. Arai’s possible involvement in his wife’s murder was difficult to prove after ten years without a body; investigators hoped that breaking Shima would make Sekine easier to pursue.

When Takada and two associates appeared at Shima’s house after a police officer left his watch, Shima fled to the police station. He begged the police to watch his home around the clock, then left when they could not promise to do so. His whereabouts became unknown to Takada, Sekiguchi, and the Saitama Prefectural Police. With Arai in custody but Shima gone, the investigation stalled again. The recordings arrived into that impasse: the Consigliere handed several tapes to Sekiguchi, drawing on the same unusual yakuza information network that had enabled the quiet contact with Arai.

What the Tapes Contain

The audio quality was poor, and much of the conversation between Arai, Sekine, and Shima was coded. The recordings therefore did not function as a simple, self-explanatory confession. Some meanings remained uncertain, while others seemed plain enough to guide investigators. In a probable reference to Endo’s disappearance, Shima reassured Arai that there was no problem, described the body as hidden, and placed it in Gunma Prefecture. He also referred to other dead bodies. In another passage, he described driving Akio Kawasaki’s car to Tokyo Station and abandoning it in the parking lot; the conversation implied that he had helped transport Kawasaki’s corpse.

These details were leads, not a complete reconstruction. The tapes did not, in the narrator’s assessment, contain anything damning on their own. Their value lay in the combination of names, references to bodies, and a specific account of where a car had been left. The material could be taken into an interrogation room and used to question Shima, but without Shima there would be no questioning—and, as Sekiguchi understood the problem, no case. The recordings sharpened the route investigators needed to follow while also exposing how much depended on a witness they could no longer find.

Evidentiary Limits and Significance

The tapes’ importance rests on an imbalance: their sound was difficult to interpret, yet their fragments were specific enough to alter investigative priorities. Arai’s initial boast suggested a direct admission by Sekine; the tapes as later heard supplied a more complicated picture of coded discussion and incriminating implications. The gap between those accounts is part of the evidence, not a reason to treat every reported claim as established fact. The recordings supported questions about Endo, Shima, and Kawasaki, but did not by themselves settle who had done what.

Their circulation also depended on personal networks rather than a straightforward handoff through official channels. Kimiko’s account came from a bar regular repeating what Arai had said; the Consigliere found Arai and later delivered the audio to Sekiguchi; and Sekiguchi had to weigh what disclosure to Takada might provoke. The book elsewhere stresses that revealing organizational secrets or cooperating with a reporter can cost a yakuza his life, while a police officer who leaks information may face prosecution or lose his job. That broader risk helps explain why the tapes move through layers of trust and concealment, though it does not establish who recorded them or how they were obtained.

In November, Sekiguchi left the team and returned to the Anti–Organized Crime Division. With Shima missing, the unspoken assumption was that he had been killed and the case would remain unsolved. At that point, the tapes had not produced an arrest of Sekine or resolved the disappearances. Their lasting role in the account is narrower and more consequential: they transformed fragments of rumor into testable investigative leads, while making clear that a recording, however suggestive, could not replace the missing witness whose knowledge gave it meaning.