Koseki: Japan’s Family Registers

Proof of Identity

In Japan, information about citizens’ births, marriages, deaths, and other important matters is recorded on a koseki, or family register. Married couples, who must share the same family name under Japanese law, and their unmarried children appear on the same document. The koseki provides proof of identity, in the same way that papers like birth certificates do in other countries. When important life events take place, such as the birth of a new family member, citizens are required to notify the authorities and have their koseki updated.

Each register has a designated honseki corresponding to the official address of the domicile or legal residence of the person in question; this address determines the municipality that formally maintains the document. It is not necessary to actually live there, and it is possible for registered persons to change their honseki if desired, such as when getting married and starting a new household.

Foreign nationals residing in Japan do not have a koseki. Even when they marry Japanese citizens, they are not officially added to the koseki so long as they maintain their foreign nationality, although their names are appended to the Japanese spouse’s record as additional notes. Children in an international marriage who obtain Japanese citizenship can be added to the Japanese parent’s register with the submission of the appropriate paperwork.

(Originally written in English. Banner photo © Pixta.)