A U.S. man whose marriage to his Japanese husband is legally recognized in his country sued the Japanese government on Wednesday for the same right to stay that a heterosexual couple would get, saying he was being denied a family life.

According to Japanese law, foreign nationals married to Japanese in heterosexual marriages are granted long-term residence status upon arrival in Japan, but those in same-sex marriages are not.

Though nearly two dozen Japanese cities, towns and wards issue certificates recognizing same-sex partnerships, they lack legal standing.

Japan remains deeply conservative and the constitution says marriage is between a man and a woman.