Japanese family register (koseki)

The Japanese family register (koseki) is the state record through which a person’s identity and family status become administratively legible. In the novel, it is more than a record of births, marriages, and deaths: it can confer recognition, leave people uncounted, and be manipulated to make one person live under another’s name. Its power is clearest in the contrast between the official certainty of documents and the unstable identities they are meant to certify.

Historical Development and Purpose

The register’s history reaches back to the late sixth century, when it was used within the Ritsuryo system, an imperial bureaucracy modeled on China, chiefly for policing and tax collection. In the Edo period, it expanded into a means of monitoring religious affiliation and suppressing Christianity. Records associated people with Buddhist temples and gathered more information about individuals, including birth, marriage, adoption, address, occupation, and death. Yet registration was never complete: people living outside settled systems, including vagrants, could remain unaccounted for.

The assumption that people were attached to a particular place became harder to sustain when freedom of movement was recognized in the late nineteenth century. During the Meiji period, a modern register was introduced for census purposes, conscription, and taxation. Those demands also gave people reasons to abandon or falsify their records. The system therefore carries a historical tension: it makes populations knowable to government, while the burdens of being known can encourage evasion and identity change.

Gaps, Exclusion, and State Recognition

The novel connects the register’s omissions to the problem of people who cannot establish a recorded identity. Nakakita explains that some postwar residents were left without registers after records in government offices were destroyed by American firebombing and the loss went unreported. Later archival safeguards placed copies in Regional Affairs Bureaus and digitization was underway, but those improvements did not resolve every gap. Children could still lack registration under the three-hundred-day problem.

Under the rule discussed in the novel, a child born within three hundred days of a divorce was legally presumed to be the former husband’s child. A woman who had left an abusive marriage and had a child soon afterward with a new partner might avoid filing a birth notification rather than have the former husband recorded as the father. The child could then enter life without a register. The consequence is not merely a missing document: despite meeting the conditions for Japanese citizenship, such a child might remain outside the state’s records, and a death in the tsunami could likewise go uncounted. The register makes birth and death legible to official systems, so absence from it can make both appear never to have occurred.

Nakakita and Kido place these exclusions in a longer history of state management. The register once supported policing, religious control, conscription, and tax collection; Kido observes that exclusion from it could also mean exclusion from the nation’s recognized civic body. Nakakita relates that logic to Japan’s assimilation policies on the Korean Peninsula, a point with particular resonance for Kido as a naturalized Japanese citizen of Korean ancestry. In their present-day discussion, residence certificates and the My Number system are described as taking over much identity management, potentially making the family register redundant. Kido replies that linking systems may make identity exchange easier, while biometrics could make administration nearly inescapable.

Identity Exchange and Documentary Proof

The investigation into X shows that an official identity may be supported by a remarkably complete paper trail and still belong to the wrong person. X lived as Daisuké Taniguchi, married Rié, and had a child with her. Government officials accepted his marriage and death notifications and updated the register accordingly. He drove using a license, obtained medical care with health insurance, and paid pension contributions. Public records consistently identified the deceased man as Daisuké Taniguchi, and his account of growing up in Gunma appeared consistent with that identity.

The contradiction emerged through family evidence: Kyoichi Taniguchi, Daisuké’s brother, saw a photograph of Rié’s husband and insisted that the man was not his brother. The register and associated documents had validated X’s identity in public life, while the photograph and the testimony of a close relative denied it. The case makes the register both an instrument of identity and a potential vehicle for identity laundering: a name becomes effective not simply because someone claims it, but because records and institutions repeatedly recognize it.

Kido’s investigation also considers the reverse possibility: that the real Daisuké Taniguchi had disappeared into the identity of an unregistered person. If X had had no register, Kido reasoned, Daisuké might have taken that undocumented identity in exchange. In that scenario, a crime against Daisuké could be exceptionally difficult for the state to recognize. A body might be treated as unidentified, while a tsunami could wash away physical evidence altogether. The register’s absence thus creates a different kind of vulnerability from its falsification: a person may be missing not only from a family but from the administrative framework that would make the disappearance visible.

Legal Revision and Personal Consequences

After X’s death exposed the deception, Kido sought changes to Rié’s family record through the Miyazaki Family Court. Because the register listed Rié and the person recorded as Daisuké as residing at her family home, that court had jurisdiction. Kido’s petition first sought to cancel the recorded removal of Daisuké due to death, restoring him as alive in the register so that police would no longer be left with a missing-person report for someone officially listed as dead. The second request sought to remove “Daisuké Taniguchi” from Rié’s register and restore her maiden name, Takemoto. The intended result was to annul the marriage on the ground of error and erase the second marriage from her record.

The correction had consequences that could not be reduced to correcting a false name. Because the marriage would be erased, Hana, Rié and X’s child, would become legally illegitimate. The court required Rié to appear in person and requested DNA evidence establishing that X was not Daisuké Taniguchi. Kido gathered samples from X’s personal effects, including hair from clothing, nail clippings, an electric razor, and a toothbrush. Official records had made the false identity durable; undoing it required a legal process and biological evidence.

For Yuto, the return to Takemoto raised a separate question of belonging. He had already lived under several surnames: Yoneda at birth, Takemoto after Rié’s first divorce, and Taniguchi when she married X. Now in middle school, he did not want another change. His objection was practical as well as emotional: his friends and schoolmates knew him as Taniguchi, and he did not want to keep correcting them. More deeply, he worried that changing his name would add to the family’s erasure of the man he had known as his father. He pointed to the ashes still in an urn and feared that, after his father’s family had turned away from him, Rié and Yuto might forget him too. Rié’s legal name could be restored, but Yuto’s attachment to the Taniguchi name belonged to lived memory, not only to the register.

Narrative Significance

The register repeatedly exposes the difference between legal identity and personal relationship. Daisuké’s family history includes the expectation that he carry the inn after his elder brother’s failure, and the unequal demands placed on him when his father needed a liver transplant. Such family obligations take place in a world where inherited names and recorded kinship help define a person’s role, yet the novel does not treat documentary status as a complete account of love or responsibility. Yuto’s later understanding of X’s kindness makes that distinction explicit: he recognizes that his father did for him what he had wished his own father would do, while Rié adds that he also acted because he cared for Yuto.

The same tension informs Kido’s reflections on the past and love. A person’s present self is shaped by circumstances that cannot be fully conveyed in words, and a narrated past may diverge from what actually happened. In the identity case, a government register is another kind of account: authoritative and consequential, yet vulnerable to omission and fraud. The novel’s central question is not simply which name is legally correct, but what happens to people when documents, family testimony, memory, and affection tell different stories. The Japanese family register (koseki) gives the state a way to recognize a life; its gaps and revisions show why recognition cannot by itself explain who that life was.