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A koseki (戸籍) or family register[1][2] is a Japanese family registry. Japanese law requires all Japanese households (basically defined as married couples and their unmarried children) to make notifications of their vital records (such as births, adoptions, deaths, marriages and divorces) to their local authority, which compiles such records encompassing all Japanese citizens within their jurisdiction.
Marriages, divorces by mutual consent, acknowledgements of paternity of non-marital children and adoptions (among others) become legally effective only when such events are recorded in the koseki. Births and deaths become legally effective as they happen, but such events must be filed by family members or other persons as allowed by law. Loss of Japanese or foreign nationalities have to be recorded in the koseki, too.
- ^ 戸籍法 [Family Register Act] (Act 224). December 22, 1947.
- ^ "Japan's Family Registry System". U.S. Embassy and Consulate in Japan. Retrieved February 2, 2022.