Koseki: recording family status rather than an address
戸籍
Japan’s koseki records civil status and family relationships for Japanese nationals, including births, marriages and parentage. Its purpose differs from the resident record, or jūminhyō, which concerns residence.
01
Civil status and residence
Residence and civil status answer different questions
A koseki can establish registered identity and family relationships. Shinjuku’s explanation lists such information as names, dates of birth and parents. The registered domicile, honseki, may be elsewhere than a person’s home. Moving house therefore does not by itself make the koseki an updated record of that new address.
Record
Main concern
Does not establish
Koseki
Civil status and family relationships
Actual current residence
Jūminhyō
Residence and household information
The full record of civil status
One fictional person, two records
Person A: civil status and parentage → koseki
Person A: residence and household → jūminhyō
Parallel records; A is fictional, not an actual register.
Family status and residence information belong to different records. Conceptual illustration, not an official form.
The first-listed person is not a household ruler
The hittōsha is the first-listed person whose name identifies the register. That listing survives the person’s death. It grants no authority over relatives and differs from the household head recorded on a resident record.
02
How the register changed
Earlier registers served other systems
Edo-period religious affiliation and population registers recorded household members alongside their temple affiliation. Hachioji’s historical examples include ages, relationships and servants. A nationwide system followed the 1871 register law; the compilation made the next year is known as the Jinshin register. Earlier records should be understood within their own administrative settings.
A postwar change in the registration unit
The earlier register used the legal household, or ie, as its unit. Under a household head it could include children, grandchildren, nephews and nieces, rather than only one married couple. The act enacted in 1947 took effect in January 1948, establishing a married couple and children sharing their surname as the basic unit; current municipal guidance specifies unmarried children. Existing registers were subsequently recompiled, rather than all being replaced on the law’s first day. The change helps distinguish the earlier household system from postwar registration. Later changes also altered the medium of the record. The 1994 legal reform allowed computer processing. Itabashi adopted it in November 2004, replacing vertical prose entries with horizontal, itemised records. This change in recording format differs from the earlier change in the family unit.
A change in the registration unit
Earlier ie unit: household head and members, potentially several generations
Postwar principle: couple and unmarried children sharing surname
Earlier volumes subsequently recompiled
A sequence of institutional change, not one family’s personal record.
Historical records need a historical reading
A koseki is not an unrestricted family directory. Shinjuku’s current guidance distinguishes requests by a person concerned, relatives, representatives and other parties. A representative must establish authority; being a sibling alone does not remove all other conditions. Historical access provisions need to be read within their own period. The original 1947 text cannot determine present eligibility to obtain another person’s record.
Check your understanding
Does a move automatically change honseki?
No. A change of residence and a change of registered domicile are separate matters.
Does the first-listed person change on death?
Shinjuku states that the listing is not changed simply because that person has died.
Does one koseki contain an entire extended family?
No. The present basic unit is a married couple and their unmarried children sharing the surname.
