Japan's Democratic Party, the main opposition party in the Japanese Parliament, submitted a bill to approve same-sex marriage, hoping to pile pressure on the government before the country hosts the Group of Seven (G7) summit in May.
The bill, which would revise the Civil Code of laws, is effectively a symbolic measure because the ruling coalition wields a significant majority and has struggled even to agree on measures outlawing discrimination against sexual minorities.
Japan is the only G7 nation that does not recognize same-sex marriage and Prime Minister Fumio Kishida has come under increasing scrutiny over LGBTQ protections in recent weeks.
Kishida has taken heat for expressing hesitation in legalizing same-sex marriage saying that it would fundamentally change society and people's values.
Japan's 1947 constitution stipulates that "marriage shall be only with the mutual consent of both sexes," although recent polls show a majority of Japanese favor recognizing same-sex marriage.