Koseki: Japan's Family Register Explained
The koseki (戸籍, family register) is Japan's household-based civil register, recording the nationality and family relationships of Japanese nationals from birth to death.123 Anyone who marries a Japanese national, has a child with one, or settles an inheritance in Japan will eventually need a copy of one, even though foreign residents are never listed on it as members in their own right.
Procedures, fees, and requirements can change. Confirm current details at the Ministry of Justice or its Legal Affairs Bureau.
Overview
The koseki records a Japanese national's nationality and family relationships, including marriage, parentage, siblingship, and adoption, as public documents from birth to death.12
Administering authority is split by statute. The mayor or head of each municipality (市町村長) administers koseki affairs as a delegated statutory function. The 法務省 (Hōmu-shō, Ministry of Justice) sets the processing standards municipalities must follow, and the 法務局 (Hōmukyoku, Legal Affairs Bureau) with jurisdiction over a given municipal office may request reports, give advice, or issue instructions where needed.2
The original register is kept at the city or town hall; a duplicate is preserved at the Legal Affairs Bureau with jurisdiction over that office.2
Anyone who marries a Japanese national, has a child with one, settles an inheritance in Japan, or is considering naturalization will eventually need to understand how this system works. As later sections explain, foreign nationals are never listed on a koseki in their own right.
How the Koseki Is Structured
A koseki is created per married couple, together with any children who share that couple's surname. It is not created per individual.2
There is a statutory exception, and it matters. When a Japanese national marries a foreign national, or when a person without a spouse needs a new register, the koseki is created for that one person alone, plus any children sharing that person's surname, rather than for a couple.2 This exception, written into the Family Register Act itself, is the statutory root of the foreigner anomaly covered later in this article.
The person listed first in a koseki, called the 筆頭者 (hittōsha, head-of-register entry), is the one whose name and honseki (本籍, registered domicile) identify the entire register. This remains true even after that person is later removed from the register, for example by death.2
Names are ordered within a koseki: first, whichever spouse's surname the couple adopted at marriage; second, the other spouse; third, children in birth order.2 Marriage normally creates a new koseki for the couple, unless one spouse is already the hittōsha of an existing register, in which case the other spouse simply joins it.2
Each person's entry records their name, date of birth, the cause and date they entered the register (birth, marriage, adoption, and so on), their birth parents' names and relationship to them, and, if adopted, their adoptive parent's name and relationship.2
The diagram below shows how one koseki register groups a household's entries together, distinct from the honseki that anchors where the register is filed.2
Honseki: The Registered Domicile Is Not Your Address
Honseki (本籍) is the administrative location where a household's koseki is registered. The Family Register Act treats it as something a household establishes within a municipality's area; it is not tied to where the household actually lives.2
Honseki is distinct from a resident's actual living address, which is instead recorded in the jūminhyō (住民票, residence record), a separate system.4
Koseki-Tohon vs Koseki-Shohon: The Two Document Types
A koseki tōhon (戸籍謄本) is a full transcript containing every person recorded in that koseki. A koseki shōhon (戸籍抄本) is an individual extract containing only a portion of those persons, typically a single household member.52 Both carry the same legal evidentiary weight; they differ only in how much of the register's content each shows.5
Since computerization of family registers, these documents carry formal names as well.
| Common term | Formal term | Covers |
|---|---|---|
| Koseki tōhon (戸籍謄本) | Zenbu jikō shōmeisho (全部事項証明書), "certificate of all matters" | Every person recorded in the register |
| Koseki shōhon (戸籍抄本) | Kojin jikō shōmeisho (個人事項証明書), "certificate of individual matters" | A single specified person in the register |
The statute's own umbrella term for both is 戸籍謄本等 (koseki tōhon tō), defined as a transcript, an extract, or a certificate of specific matters recorded in the koseki.2
Not everyone can request a copy of a given koseki without explanation.2
| Requester | Can request without stating a reason | Notes |
|---|---|---|
| The person recorded (including someone since removed from the register) | Yes | Narrow exceptions apply |
| That person's spouse, or their direct ascendants or descendants | Yes | |
| Any other third party | No | Must state a qualifying legal reason, such as exercising a legal right, at the time of request |
What the Koseki Is Used For
The following situations are the ones where a reader is most likely to be asked for a koseki copy. What each situation actually requires differs sharply, and one of the three below is not really a koseki matter at all.
Marriage, Inheritance, and Name-Change Uses
Registering a marriage in Japan updates or creates a koseki entry for the couple, as described above.2 This research found no primary source requiring a marrying couple to submit a copy of their own koseki as part of that marriage registration itself. The koseki tōhon requirement that does exist applies to a separate procedure, a foreign spouse's visa application, covered later in this article.
Inheritance is the clearest case for the full tōhon. Identifying every legal heir of someone who has died requires collecting that person's koseki tōhon from birth to death, since marriages, divorces, and adoptions that created or removed heir relationships may be scattered across several registers if the person changed honseki or koseki during their lifetime.6 A complex estate, especially one spanning multiple honseki changes over a lifetime, is often worth a specialist's help alongside this system.
The Legal Affairs Bureau's Statutory Heir Information Certification System (法定相続情報証明制度) lets an applicant submit the collected birth-to-death koseki tōhon once, along with a family-relationship chart, and receive free certified copies usable for inheritance registration, bank account closures, tax filing, and pension procedures (as of 2024-04-01; confirm current figures with the Legal Affairs Bureau). The system itself has existed since 2017-05-29.6
Changing the given-name portion of a name recorded on the koseki requires family court permission first. The court requires a "justifiable reason": evidence that keeping the current name would cause genuine difficulty in daily life, not simply personal preference or sentiment.7 The applicant may submit the change for entry into the koseki only after the court grants permission.
Passport, Employment, and School-Enrollment Uses
These three contexts are often grouped together as everyday reasons to request a koseki, but the document each actually requires, if any, differs sharply.
| Context | Koseki document required | Notes |
|---|---|---|
| Passport application | Koseki tōhon (full transcript) only | Shōhon, an amended-register copy (改製原戸籍), and the koseki's fu-hyō (附票) attachment are not accepted8 |
| Employment | None; requesting one is discouraged | Fair-hiring guidance treats this as a red flag, not a routine ask9 |
| School enrollment | Not applicable | No koseki document was found to be required; jūminhyō, the residence record described earlier in this article, is the relevant document for matters tied to where a family lives |
The passport rule is recent: only the full tōhon has been accepted since March 27, 2023 (as of 2023-03-27)8.
Ministry of Health, Labour and Welfare guidance states that hiring decisions should rest solely on an applicant's aptitude and ability, and that a person's honseki and birthplace are "matters for which the applicant bears no responsibility." Requesting a koseki tōhon or shōhon from a job applicant, or asking about their honseki, is treated as a potential fair-hiring violation.9 Some employers reportedly still ask informally, but this is not a legitimate or expected step in a Japanese hiring process.
This research found no basis for koseki as a school-enrollment document. Residence registration through the jūminhyō system, not the koseki, is the relevant document for matters tied to where a family actually lives.4
Foreigners and the Koseki: The Anomaly Explained
Foreign nationals are never listed as members of a koseki in their own right. The Family Register Act registers Japanese nationals only, and the statute's own text uses the term 外国人 (foreign national) specifically to define the case that receives different treatment.2
When a Japanese national marries a foreign national, a new koseki is created for the Japanese national alone, plus any children who share that person's surname. The foreign spouse does not get a koseki of their own, regardless of how long the marriage lasts or whether children are born.210
The Ministry of Justice's own guidance on international-marriage koseki matters confirms this in plain terms: no koseki is created for the foreign national. Instead, the fact that the Japanese national married that foreign national, including the foreign national's name, date of birth, and nationality, is recorded on the Japanese national's own koseki.10
How a Foreign Spouse Appears on a Japanese Citizen's Koseki
The foreign spouse's name, nationality, and date of birth are recorded in the "identity matters" (身分事項) section of the Japanese spouse's koseki, as part of the marriage entry.10 Practitioner sources describe this name as rendered in katakana on that entry, though this specific mechanical detail has not been independently confirmed against a Ministry of Justice circular in the research behind this article.11
The diagram below shows the asymmetry: the marriage is recorded on the Japanese spouse's koseki, but the foreign spouse's own registered status runs through a different document entirely.
Why This Matters Beyond Paperwork
The Japanese spouse's koseki tōhon showing the marriage is a required document for the foreign spouse's "Spouse or Child of Japanese National" status-of-residence application, whether that is an initial certificate of eligibility, a status change, a renewal, or an acquisition of status.12 If the marriage is not yet reflected in the koseki at filing time, the applicant must submit a marriage-notification acceptance certificate (婚姻届出受理証明書) alongside the koseki tōhon instead.12
Good to know
Requesting a Copy Is a Separate Topic
Obtaining a copy of a koseki, whether a tōhon or a shōhon, is a procedural topic on its own and is covered in full in a separate article. Three broad paths exist: an in-person request at a municipal counter, a request by mail, and, where available, an automated request from a convenience-store multifunction copier.213
A March 1, 2024 amendment to the Family Register Act introduced "wide-area issuance" (広域交付): a resident can now request certain koseki certificates in person at any municipal counter nationwide, not only at the counter of the household's own honseki municipality (as of 2024-03-01; confirm current figures with the Ministry of Justice).14
Wide-area issuance and convenience-store issuance are not the same service, even though secondary sources sometimes describe them as though they were. Wide-area issuance is the March 2024 change described above, and it is an in-person, counter-only service; it is generally not available at convenience-store kiosks or unstaffed satellite counters. Convenience-store issuance is a separate, older system that dispenses certificates from a multifunction copier using a My Number card, and it works only where the household's honseki municipality has opted into the program (as of 2025-12-25)13.
If the requester's residence differs from their honseki, the requester must complete an advance registration with the honseki municipality, typically taking a few business days, before a convenience store will dispense anything. No primary source found in this research describes the March 2024 revision itself as an expansion of convenience-store kiosk issuance; the Ministry of Justice's own page on that amendment describes the wide-area counter service only.1413
"No Koseki" Does Not Mean "No Legal Status"
Lacking a koseki of one's own does not put a foreign resident in any kind of legal gap. Since July 9, 2012, foreign residents lawfully in Japan for more than three months, including mid- to long-term residence card holders and special permanent residents, are registered in the same Basic Resident Register (住民基本台帳) system as Japanese nationals and are issued a jūminhyō (as of 2012-07-09)4. This followed the same reform that abolished the older, separate Alien Registration system.4
The jūminhyō, not the koseki, is the document that establishes a foreign resident's registered residence in Japan.
Requesting From a Distant Honseki Municipality
When a household's honseki municipality is not where the household actually lives, requesting a copy in person at the honseki municipality's own counter is impractical. Three alternatives exist.
A mail request is available by statute at any time, regardless of distance.2 An in-person request at any municipal counter nationwide has been possible since the March 2024 wide-area-issuance change (as of 2024-03-01)14, though this option covers koseki tōhon, joseki tōhon, and modified-register tōhon, not koseki shōhon. Convenience-store issuance remains an option only if the honseki municipality participates in that program and the requester has completed the required advance registration (as of 2025-12-25)13.