Japan’s Parliament voted Friday to preserve male-only succession to the imperial throne, reinforcing a centuries-old rule at the heart of a monarchy whose origins are said to stretch back about 1,500 years.
The move came through revisions to the Imperial House Law, a statute dating to the 1800s. Experts have warned that keeping succession restricted to males from the paternal line could accelerate the decline of Japan’s already small and aging imperial family, according to the Associated Press.
In an effort to expand the pool of future heirs, the changes permit distant male relatives to be adopted into the imperial family so they can father successors. Still, the throne remains limited to men with imperial blood. The revisions also allow princesses to keep their royal status after marrying commoners.
The parliamentary approval comes despite growing public calls for Princess Aiko, the 24-year-old daughter of Emperor Naruhito, to one day succeed her father — a path now ruled out under the updated law.
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,” Junichiro Tsujimaru, a 78-year-old founder of a sushi chain, told the AP.
Under the current line of succession, the 66-year-old emperor’s younger brother stands next in line. He is followed by the emperor’s 19-year-old nephew, Prince Hisahito, and then by the emperor’s 90-year-old uncle.
Prince Hisahito is the only boy born into the imperial family in four decades, and just five of its 16 adult members are men.
Prime Minister Sanae Takaichi and other conservatives say the male bloodline is the source of the emperor’s authority and 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)
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“It’s a declaration to prevent female monarchs … and to defend the male-lineage at all costs,” Hideya Kawanishi, a Nagoya University expert on monarchy, told the AP. “They cannot say it’s male chauvinism, so they call it tradition.”
Chizuko Ueno, a prominent feminist and sociologist, recently suggested it was ironic that Japan’s first female prime minister was the one to ensure male-only succession.
Ueno said the new rules “treat male royals as stallions and put female royals under pressure as ‘childbearing machines’ to produce male offspring.”
Japan has had eight empresses descended from the male line in its centuries-long history as a hereditary monarchy. The last woman to reign was Empress Go-Sakuramachi, who sat on the throne from 1762 until 1771, when she abdicated 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 eliminated in 1890 under the original Imperial House Law.
That change was carried over into the modern Imperial House Law, enacted in 1947, the same year Japan’s new constitution stripped the emperor of governing authority after the country’s defeat in World War II.
Like Britain’s royal family, Japan’s imperial family remains an important national symbol.
