Japan Locks In Male-Only Imperial Succession Despite Demographic Crisis

TOKYO — Japan’s Parliament voted on Friday to legally enshrine male-only succession for the imperial throne, a decision that cements patrilineal inheritance for a monarchy tracing its historical origins back roughly 1,500 years.

By revising the Imperial House Law, which has roots dating back to the late 1800s, lawmakers chose to preserve the male-only line of succession. This decision comes despite warnings from demographic and legal experts who caution that limiting the throne to paternal-line men will hasten the decline of Japan’s shrinking and aging imperial family.

Under the newly approved revisions, Parliament introduced measures to address the dwindling pool of eligible heirs. Distant male relatives will now be allowed to be adopted into the imperial family to father future successors. However, strict rules remain in place to ensure that the throne is limited exclusively to men with royal blood. In another significant shift, the revisions will allow princesses to retain their royal status after marrying commoners—a change aimed at slowing the rapid contraction of the household.

The legislative move has disappointed a large segment of the Japanese public. Many had been calling for Princess Aiko, the 24-year-old daughter of Emperor Naruhito, to be allowed to succeed her father. Under the newly passed rules, that path is now an impossibility.

Japan’s Princess Aiko, left, the daughter of Emperor Naruhito and Empress Masako, arrives to mark the 110th anniversary of the death of the wife of former emperor Meiji at Meiji Shrine in Tokyo, on April 10, 2024. (Kazuhiro Nogi/Pool Photo via AP)

“The emperor is a symbolic figure, and I don’t see why women cannot serve in the role,” said Junichiro Tsujimaru, a 78-year-old sushi chain founder, reflecting a widely held sentiment among the public.

### A Fragile Line of Succession

The decision highlights the precarious state of the world’s oldest continuous hereditary monarchy. Under the current legal framework, the next in line to succeed the 66-year-old Emperor Naruhito is his younger brother. Following him is the emperor’s 19-year-old nephew, Prince Hisahito, and finally, the emperor’s 90-year-old uncle.

The demographic reality is stark: Prince Hisahito is the only boy to be born into the imperial family in four decades. Currently, only five of the 16 adults in the imperial family are men, leaving the dynasty highly vulnerable to a lack of eligible heirs in the next generation.

Despite these pressures, Prime Minister Sanae Takaichi and other political conservatives have fiercely defended the status quo. They argue that the uninterrupted male bloodline is the ultimate source of the emperor’s authority and historical legitimacy.

Japan’s Prime Minister Sanae Takaichi speaks during a news conference at the prime minister’s office in Tokyo, Oct. 21, 2025. (Eugene Hoshiko)

Critics, however, view the decision as a step backward that ignores modern social realities.

“It’s a declaration to prevent female monarchs … and to defend the male-lineage at all costs,” said Hideya Kawanishi, an expert on the monarchy at Nagoya University. “They cannot say it’s male chauvinism, so they call it tradition.”

Chizuko Ueno, a prominent feminist and sociologist, pointed out the irony that Japan’s first female prime minister, Sanae Takaichi, was the political leader who ultimately ensured the continuation of male-only succession.

Ueno criticized the new rules, stating they “treat male royals as stallions and put female royals under pressure as ‘childbearing machines’ to produce male offspring.”

### Historical Precedents and Modern Laws

While conservatives frame the male-only line as an ancient, unbroken tradition, Japan’s history reveals a more complex picture. The country has had eight empresses descended from the male line during its centuries-long history. The last woman to reign was Empress Go-Sakuramachi, who sat on the throne from 1762 until her abdication in 1771 in favor of her nephew.

Japan’s Prince Hisahito, right, attends his coming-of-age rituals on his 19th birthday at the Imperial Palace in Tokyo, on Sept. 6, 2025. (Japan Pool/Kyodo News via AP)

Female eligibility for the throne was first legally eliminated in 1890 under the original Imperial House Law during the Meiji Restoration, an era when Japan heavily modernized its legal systems.

This restriction was carried over into the modern Imperial House Law enacted in 1947. That same year, Japan’s post-World War II constitution stripped the emperor of all governing authority, redefining the monarch as a purely ceremonial symbol of the state and the unity of the people.

Much like Britain’s royal family, Japan’s imperial family holds no political power but remains a deeply revered national symbol, representing historical continuity and cultural identity. The new legislative revisions ensure that while the family’s structure may adapt slightly to survive, its strictly patrilineal core remains unchanged.