The Osaka High Court has ruled that the Japanese family registration system, which only recognises “male” and “female” gender categories, violates the equality principle set out in the country’s constitution. In a landmark decision issued on May 8, the court determined that the absence of a non-binary option in Japan’s family registry system breaches Article 14 of the constitution, which guarantees protection against discrimination.

Japan’s family registry system, known as the “koseki”, is a mandatory national database used to record major life events including births, deaths and marriages. The system is administered by local municipalities and plays a central role in legal identification and family status.

This case centred on a 50-year-old non-binary resident of Kyoto who filed a petition in December 2024 seeking to amend their entry in the koseki. The petitioner requested that the designation “eldest daughter” be changed to a gender-neutral term such as “eldest child” in order to better reflect their identity.

The Kyoto Family Court initially rejected the request. Although the Osaka High Court upheld that decision, presiding Judge Masahiro Oshima stated that the broader issue of non-binary exclusion from the registry system was unconstitutional and should be reconsidered nationally.

The court ruled that allowing the individual petitioner’s gender marker to be altered immediately would not be appropriate under the current nationwide framework. However, it added that if a non-binary option were introduced in future, the petitioner’s request should be reviewed again.

According to Japanese newspaper The Asahi Shimbun, the court stated that it is “appropriate to open a path to allow corrections in a form that aligns with an individual’s gender identity”. The judges also recognised the importance of gender identity as a protected legal interest.

The court stated that gender identity is “directly linked to an individual’s personal existence, making it a significant legal good,” according to reporting by The Japan Times.

Advocates for LGBTQ+ rights in Japan have described the ruling as a major breakthrough in the country’s legal treatment of non-binary people.“The existence of nonbinary gender has been legally unrecognised,” attorney Shun Nakaoka told The Japan Times. “(The High Court’s statement on gender identity) is a huge step toward legal recognition.”

While the ruling does not immediately change Japan’s registration laws, campaigners say it represents one of the clearest judicial acknowledgements yet of non-binary identities under Japanese constitutional protections.