Japan's parliament has passed a landmark revision to its Imperial House Law, reinforcing the principle of male-only succession to the Chrysanthemum Throne while introducing limited measures to address the imperial family's rapidly shrinking numbers. The upper house approved the bill by a large majority on Friday, with support from several parties including the ruling Liberal Democratic Party and its coalition partners, while opposition came from the Constitutional Democratic Party, the Communist Party, and others.
The revised law allows the imperial family to adopt unmarried male relatives aged 15 or older from 11 former imperial branch families — families that renounced their royal status in 1947, largely to ease the postwar financial burden on the monarchy. Crucially, adopted men themselves will not be eligible to ascend the throne, but any sons they father after adoption would be. The law also permits female members of the royal family to retain their royal status and continue carrying out official duties if they marry commoners, reversing a rule that previously stripped them of their titles upon marriage. Princess Mako, a niece of Emperor Naruhito, gave up her status in 2021 to marry a college boyfriend and later moved to New York.
The revisions do nothing to change the fundamental bar on women becoming emperor, despite an Asahi Shimbun poll from May showing 72 per cent of Japanese respondents in favour of female succession. Princess Aiko, the 24-year-old and only child of Emperor Naruhito, remains ineligible to inherit the throne. The line of succession currently runs to Naruhito's younger brother, 60-year-old Crown Prince Akishino; then to Akishino's 19-year-old son, Prince Hisahito; and then to Naruhito's 90-year-old uncle — the last eligible candidate. If Hisahito has no male child, the line of succession would otherwise end. Of the imperial family's 16 current members, only five are men.
The legislation has drawn sharp criticism from scholars, former imperial family members, and parts of the public. Hideya Kawanishi, a monarchy expert at Nagoya University, described the law as "a declaration to prevent female monarchs and to defend the male-lineage at all costs." Feminist scholar Chizuko Ueno called it ironic that Prime Minister Sanae Takaichi — Japan's first female prime minister and a leading proponent of male-only succession — was driving the policy. Former imperial family member Asahiro Kuni, 81, said he would advise his grandchildren to refuse any approach from the palace, questioning whether young people who had grown up in freedom could adapt to the constraints of royal life.
The revision marks the first substantive amendment to the main text of the Imperial House Law since 1949, and reflects the tension between preserving a hereditary institution whose mythic lineage is said to span more than 2,600 years and the practical realities of a fast-ageing, dwindling imperial family. Historians note that the male-only system functioned historically in part because emperors kept concubines — a practice that ended roughly a century ago. A government proposal to allow female monarchs was floated in 2005 but was shelved following the birth of Prince Hisahito, the first male royal baby born in four decades. Parliament's accompanying resolution calls for continued discussion on ensuring stable succession, leaving the door open — at least nominally — to future reform.