Japan's Prince Hisahito becomes 1st royal male to turn 18 in 40 years; know why its historic milestone

In a big milestone for Japan's royal family, Prince Hisahito turned 18 on Friday, becoming the first male royal family member to reach adulthood in almost four decades.

It is a significant development for a family that has ruled for more than a millennium but faces the same existential problems as the rest of the nation — a fast-aging, shrinking population.

Hisahito, who is set to become the emperor one day, is the nephew of Japanese Emperor Naruhito. His father, Crown Prince Akishino, was the last to do so, in 1985.

Prince Hisahito, the youngest among the 17-member all-adult imperial family, is one of only four men in the family.

His position as the last heir in line presents a significant challenge for a system that excludes empresses. Discussions within the government are ongoing to address how to maintain stable succession without depending on female members.

Here's what you need to know

The 1947 Imperial House Law, which largely preserves conservative pre-war family values, only allows a male to succeed to the throne and forces female royal members who marry commoners to lose their royal status.

Princess Aiko, who is his older cousin and the only child of Naruhito and Masako, a former diplomat educated at Harvard, is the public's favored choice for the future empress. However, current legislation bars her from assuming the role despite her direct lineage.

The imperial succession hierarchy can be intricate: Naruhito holds the position of emperor, followed by his brother, Akishino, in second place. Next in line is Hisahito, the son of Akishino.

An earlier proposal to permit an empress following Aiko's birth was set aside immediately after Hisahito's arrival in 2006.

“Right now I would like to cherish my remaining time in high school," Hisahito said in a statement. He has long been interested in insects and even co-authored an academic paper on a survey of dragonflies on the grounds of his Akasaka estate in Tokyo, the statement said.

A largely conservative government-commissioned panel of experts in January 2022 recommended that the government propose allowing female members to keep royal status after marriage as a way to prevent the declining population within the imperial family, while adopting male descendants from now-defunct royal families to continue the male lineage with distant relatives.

Critics say those measures would have a limited effect as long as the male-only succession is maintained because it was workable largely with the help of concubines in the pre-modern era. 

(With inputs from PTI)