TOKYO — In a significant milestone for Japan's royal family, Prince Hisahito turned 18 on Friday, becoming the first male royal family member to reach adulthood in nearly 40 years.

His coming of age marks a critical moment for the imperial family, which has ruled Japan for over a millennium but now faces existential challenges similar to the rest of the country, including a rapidly aging and shrinking population.

Prince Hisahito, who is set to become emperor one day, is the nephew of Japanese Emperor Naruhito and the son of Crown Prince Akishino, who was the last male family member to reach adulthood in 1985. Hisahito is the youngest member of the 17-member imperial family, which currently includes only four men.

His status as the last heir apparent highlights a significant issue for the imperial system, which does not permit empresses. The Japanese government is currently debating ways to maintain a stable line of succession without depending on female members.

The 1947 Imperial House Law, which upholds conservative pre-war family values, restricts succession to male heirs and forces female royals who marry commoners to forfeit their royal status. This rule has been particularly contentious given the public's support for Princess Aiko, the only child of Emperor Naruhito and Empress Masako, as a potential future empress. However, the law bars her from ascending the throne.

The imperial succession chart is straightforward: Emperor Naruhito currently holds the throne, followed by his brother Crown Prince Akishino, with Hisahito next in line. A previous proposal to allow an empress after Aiko's birth was quickly abandoned following Hisahito’s birth in 2006.

“Right now I would like to cherish my remaining time in high school,” Hisahito said in a statement, highlighting his long-standing interest in insects and his co-authorship of an academic paper on dragonflies at his Tokyo estate. — Agencies