2007 Nakano Ward Household Registration Exchange Case

The 2007 Adachi family-register exchange case is a criminal case Kido finds while searching for a precedent that might explain how a person could live under another man’s legally recognized identity. Its importance lies in the gap it exposes between identity as a lived reality and identity as documented by the state: the men did not merely use false names but mutually exchanged family registers, with a broker arranging the transaction. The case gives Kido a plausible lead in his investigation of the man who died as Daisuké Taniguchi, though it does not by itself establish that the two situations were connected.

Discovery and Background

Kido encounters the case after his inquiry has stalled. A conversation with Nakakita about people left outside official records, including children without family registers, has made Kido consider how registration can determine whether a person is recognized by public institutions. He follows that discussion by researching criminal cases involving social security and comes across a ruling from six years earlier—dated to 2007, the year Daisuké Taniguchi moved out of his Osaka apartment and X appeared in Town S.

The coincidence of year and the case’s unusual method give Kido a new line of inquiry. Rather than treating the deception as ordinary use of an assumed name, he wonders whether the missing Daisuké and X could have encountered one another through a similar exchange. At this point, that is a hypothesis, not a conclusion.

The Exchange and Its Participants

The case involved a fifty-five-year-old man in Tokyo’s Adachi ward who falsely presented himself as another man, then sixty-seven, and received the older man’s pension. The arrangement went beyond impersonation: the two men had agreed to exchange family registers. The older man sought the exchange to persuade his fiancée, a woman in her thirties, that he had never been married and was ten years younger than he really was.

The legal consequences described in the ruling fell on the fifty-five-year-old participant. He was found guilty of false entry in an original notarized electronic document and of sharing that false document, and received a one-year prison sentence suspended for three years. The case thus connects a private arrangement between two men to offenses involving official records and pension receipt: the exchanged identity could be presented not only in personal life but also in dealings with public systems.

The Broker and Kido’s Lead

Kido is particularly struck by the presence of a third participant: a broker who had arranged the register exchange. Although initially given only a suspended sentence as an accomplice, the broker was later arrested in connection with an investment scam involving fundraising for a nonexistent business and sentenced to three years in prison. The ruling also indicated that he had arranged numerous other exchanges and charged a handling fee for each one.

Further research establishes that the broker is serving his sentence at Yokohama Prison, only thirty minutes by train from Kido’s home. Kido arranges a visit and writes to say that he wants to ask about an incident from six years earlier. The man replies that it would be his pleasure to meet, an unexpectedly welcoming response from someone Kido has never met. The case therefore turns the investigation from an abstract puzzle about identity into a search for a specific intermediary who may be able to explain how such exchanges were arranged.

Significance in the Investigation

The case provides a practical model for understanding how an exchanged family register might allow one person’s identity to stand in for another’s. Elsewhere in Kido’s investigation, public records appear to affirm that the deceased man was Daisuké: officials accepted marriage and death notifications, while his driving, medical, and pension records also bore that identity. Yet Kyoichi Taniguchi identified the man in a photograph as someone other than his brother. The Adachi case makes clear that this kind of contradiction need not be reduced to a false name spoken in everyday life; an exchange can place the deception inside the documentary system itself.

The case also sharpens the stakes of missing registration. Kido has begun to consider whether X might have lacked a family register, leaving Daisuké to disappear from official recognition in his place. The Adachi ruling shows that registers could be deliberately exchanged through an intermediary; it does not prove that this happened to Daisuké and X. Its narrative force is the credible investigative path it opens, and the reminder that official records can both confer an identity and obscure the person who lived it.