It is still impossible for couples to register a marriage without one legally assuming the other’s surname, an antediluvian restriction that was nonetheless fou

It is still impossible for couples to register a marriage without one legally assuming the other’s surname, an antediluvian restriction that was nonetheless found constitutional by the Supreme Court last year. Interestingly, a workaround for this is to marry a foreigner. Japanese who marry non-japanese citizens don't need to switch their surnames. As a data format, koseki are interesting because they are tied up with citizenship in a weird way. [1] The spouse variable only holds values of type citizen so people who marry foreigners have their spouse listed in the free-form description section. :-) This has some drawbacks but in the case of having different surnames it gets you around the restriction. [1]https://en.wikipedia.org/wiki/Koseki#Koseki_and_citizenship https://en.wikipedia.org/wiki/Koseki#Koseki_and_citizenship