Japan’s parliament enacted a historic and contentious revision to the 19th-century Imperial House Law on Friday, July 17, 2026, formally insisting that only men of paternal lineage are eligible to become emperor. This legislative move has sparked significant concern among royal watchers and experts, who fear that the rigid adherence to male-only succession could ultimately threaten the survival of the 1,500-year-old hereditary institution as the imperial family continues to shrink.
Prime Minister Sanae Takaichi, a leading proponent of the legislation, told reporters she was “deeply moved” following the enactment. Takaichi and other conservative lawmakers maintain that the male bloodline is the sole source of the emperor’s authority and legitimacy, serving as the foundational justification for the new measures. Under the revised law, while an emperor’s mother may be a commoner—as is the case with the current Emperor Naruhito—only boys born to men with royal blood can inherit the throne. The law effectively pushes the Emperor’s daughter, Princess Aiko, to the side, while allowing princesses to retain their royal status and continue their duties even if they marry commoners.
Hideya Kawanishi, an expert on the monarchy at Nagoya University, described the revision as a deliberate declaration to prevent the rise of female monarchs and to defend the male lineage at any cost. Kawanishi noted that proponents avoid labeling the policy as male chauvinism, instead framing it as a matter of tradition. Imperial Household Agency chief Buichiro Kuroda stated in a response that his agency would do everything possible to support the smooth activity of imperial family members in line with the new revisions, while remaining fully considerate of their personal feelings.
The history of the Japanese monarchy includes eight female monarchs, with the last being Empress Gosakuramachi, who reigned from 1762 to 1770. The current paternal-lineage requirement was first stipulated in the 1890 Imperial House Law, a period when Japan actively promoted patriarchal systems, and was largely carried over into the 1947 version. Historians point out that the system was historically unworkable without the use of concubines, a practice that provided half of the emperors until it was abolished about 100 years ago under Emperor Taisho, the great-grandfather of the current emperor.
The new law introduces a controversial mechanism to address the shortage of heirs: it allows for the adoption of unmarried male descendants, aged 15 or older, from distant imperial branch families, provided they are of paternal lineage. However, this proposal faces significant criticism. Imperial Household Agency official Yoshimi Ogata explained to parliament that 51 members from 11 branch families renounced their royal status in 1947 to ease the postwar financial burden on the monarchy. These individuals are at least 36 generations removed from Emperor Naruhito, having split from a common male-line ancestor 600 years ago.
Critics argue that the government is making extraordinary efforts to ensure male royals produce male emperors. Yoshinori Kobayashi, a cartoonist campaigning for Princess Aiko’s right to succeed, questioned the public’s desire to see the son of an unknown adoptee on the throne instead of the Emperor’s daughter. Furthermore, 81-year-old Asahiro Kuni, whose family renounced their royal status when he was three, told TBS television that he would advise his family to decline any such request. Kuni described the imperial life as an “enclave without human rights” where individuals cannot choose their own jobs or homes, adding that it would be cruel to force a young person to change the course of their life for such a role.
The pressure on the royal family is immense. Feminist scholar Chizuko Ueno criticized the new measures, stating they treat male royals as “stallions” and place female royals under extreme pressure to act as “childbearing machines.” Ueno specifically noted that Empress Masako, a Harvard-educated former diplomat, developed a stress-induced mental condition following the birth of Princess Aiko, largely due to public criticism regarding the lack of a male heir. Former Imperial Household Agency chief Shingo Haketa recently told Kyodo News that the monarchy’s future after Prince Hisahito is “extremely unstable.”
Currently, the line of succession includes Crown Prince Akishino, who is 60 and has reportedly expressed concerns about being too old to serve, and his 19-year-old son, Prince Hisahito. The third in line is the Emperor’s 90-year-old uncle, Prince Hitachi. Public sentiment remains divided, with many citizens expressing support for Princess Aiko, who is widely admired for her engaging personality. Some, like 78-year-old sushi chain founder Junichiro Tsujimaru, argue that as a symbolic figure, there is no reason a woman cannot serve as emperor. Yoshio Iwase, also 78, echoed this, stating that Aiko is the legitimate successor.
There is also worry that these government efforts undermine the legacy of former Emperor Akihito, who abdicated in 2019 after working to bring the monarchy closer to the people and making amends for World War II victims. Akihito reportedly supports Aiko’s succession, having previously remarked that female royals served a major role in the monarchy, a comment widely interpreted as support for female monarchs. Emperor Naruhito also expressed hope in June that discussions would reach a conclusion that gains the “understanding of the people,” a statement palace watchers viewed as a sign of his nuanced displeasure with the male-only mandate. Alongside these imperial changes, the government also enacted a law prohibiting the desecration of the national flag, a move opponents see as an attempt by Prime Minister Takaichi to silence criticism and enforce a nationalist agenda.
A government proposal in 2005 to allow female monarchs was scrapped following Hisahito’s birth.
Ueno calls the system inhumane and urges the princesses to follow Mako’s example and leave when they can.
