As discussions around the future of Japan’s imperial succession continue, the recent passage of a parliamentary bill has added a new twist to an already complex debate. On July 17, Japan’s upper house approved legislation allowing distant male relatives of the imperial family to be adopted into the line of succession. This marks the first significant amendment to the Imperial House Law since 1949, prompted by growing concerns over the dwindling number of male heirs.
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Despite this development, the new law does little to address the long-standing exclusion of women from the throne. Consequently, Princess Aiko, the only child of Emperor Naruhito, remains ineligible to ascend the imperial seat. The line of succession continues to favour male lineage, with Emperor Naruhito’s brother, Crown Prince Akishino, aged 60, next in line, followed closely by his 19-year-old son, Prince Hisahito.
The recent legislative changes aim to incorporate male descendants from 11 former imperial branches, which were disbanded after Japan’s defeat in the Second World War. By permitting these relatives to rejoin the imperial household, the government hopes to ensure a larger pool of family members ready to fulfil royal duties and public engagements.
Another notable amendment contained in the new law is the provision allowing female members of the imperial family to retain their royal status upon marrying commoners. Historically, this has not been the case; when Princess Mako, the emperor’s niece, married her partner Kei Komuro in 2021, she relinquished her titles and departed the imperial family. Mako and Komuro now reside in the United States, where they work as lawyers and welcomed their first child in May 2025.
In light of these changes, public sentiment appears to be shifting. Recent surveys indicate that a significant portion of the Japanese population favours the inclusion of female empresses within the imperial system. The prevailing stance of barring women from ascending the throne sets Japan apart from many contemporary monarchies in Europe, which have been modernising their succession laws.
For instance, in 2011, the Commonwealth realms agreed to the Perth Agreement, which abolished male-preference primogeniture. This reform allows first-born children, regardless of gender, to inherit titles. Thus, when Prince Louis was born in April 2018, Princess Charlotte retained her place ahead of him in the line of succession—a historic first for British royalty.
Currently, several European nations are guided by similar practices that support female succession. Sweden boasts Crown Princess Victoria, while Spain has Princess Leonor, Belgium is represented by Princess Elisabeth, and the Netherlands has Princess Catharina-Amalia as heirs. The modernisation of royal succession in these countries starkly contrasts the rigid traditions upheld by the Japanese Imperial Family.
The ongoing discussions surrounding the Japanese imperial succession highlight the tension between tradition and contemporary values. While the recent changes may indicate a slight shift towards inclusivity, they are not sufficient to meet the evolving expectations regarding gender equality in leadership roles.
Critics of the current succession laws argue that continued exclusion of women from the throne is an antiquated practice that does not reflect societal progress. Advocates for reform are calling for a more inclusive approach, which would affirm women’s roles within the royal hierarchy and address the increasing calls for gender parity.
As Japan contemplates its imperial future, the legacy and traditions of the imperial family remain at the forefront. While the new law offers a way to diversify the line of succession, it raises further questions about the place of women in Japan’s royal lineage and whether more substantial reforms are necessary to keep pace with global developments. The debate surrounding the potential for a female monarch in Japan is likely to continue as the nation grapples with its historical precedents and modern aspirations.