In recent decades, same-sex marriage has become legal in many countries, including the United States, Canada and parts of Europe.

In Japan — starting with Tokyo's Shibuya and Setagaya wards in November 2015 — municipal governments have begun issuing certificates that recognize same-sex unions as being equivalent to marriage, granting couples rights in such areas as hospital visits and apartment rentals. But same-sex couples are still unable to legally wed.

Mary Bonauto, an American lawyer who was a key player in the nationwide legalization of same-sex marriage in the United States, visited Tokyo earlier this month at the invitation of lawyers pushing for legislation to make that happen in Japan as well.