An openly gay assemblyman from Aichi Prefecture and his Taiwanese partner, having just registered their union in Taipei, called on Tokyo on Monday to swiftly legalize same-sex marriage to ensure equality for sexual minorities.

Takahama Municipal Assembly member Masahiro Shibaguchi, 53, of the Japanese Communist Party, and his spouse Ariel Ling-chun Liu, 38, who also lives in Japan, traveled to Taiwan to register their marriage in Taipei City's Datong District on Aug. 11.

Japan remains the only Group of Seven nation that does not recognize same-sex marriage. A number of lawsuits have been filed in the country by same-sex couples seeking to make their relationships legal.