Osaka has become the first city in Japan to officially recognise a same-sex couple as foster parents.
Unlike many other developed nations, Japan has been accused of having conservative attitudes to LGBT issues.
But officials in the city of Osaka have approved the wishes of a man in his 30s and a man in his 40s to foster a teenage boy.
The government's department of health, labour and welfare says nowhere else in the country has done anything similar.
The Japan Times reported the older of the men as saying: "I am happy we became foster parents [and recognised] as a single household, not just as individuals."
He added the boy is now "living a comfortable life".
The rules around same-sex couples adopting a child in Japan are ambiguous and it's not thought to commonly occur.
According to LGBT website Equaldex while homosexuality is legal in Japan, same-sex marriage is not recognised.
One survey on its pages suggest 42% of Japanese people support, or somewhat support gay marriage.
The Netherlands became the first country in the world to legalise same-sex marriage in 2001.
New Zealand, South Africa, Norway and Denmark, as well as others, all followed suit in the years after.
But as recently as 2010 Tokyo's governor caused outrage when he described gay people as "deficient".
Japan has only recently started addressing LGBT bullying in school.
Last month the national government updated its anti-bullying guidelines to include protection for sexual and gender diverse students.
Campaigners hope this latest step could help shift the attitudes of anti-gay sentiment in the country.