With no other young male heirs after him, Japan faces renewed calls to reconsider its male-only succession system that dates back to the 19th century.

His coming-of-age ceremony, postponed by a year so he could prepare for university entrance exams, began Saturday at his family’s residence.

There, he received a kanmuri crown from a messenger of the emperor.

“Thank you very much for bestowing the crown today at the coming-of-age ceremony,” Hisahito said, according to The Guardian. “I will fulfil my duties, being aware of my responsibilities as an adult member of the imperial family.”

At the Imperial Palace, he first appeared in traditional robes marking adulthood before donning formal attire and travelling in a royal carriage to the palace’s three shrines, Nippon reported.

His duties also include visits to Ise Shrine, the tomb of Japan’s first emperor Jinmu, and the mausoleum of his great-grandfather, Emperor Showa.

He will also meet Prime Minister Shigeru Ishiba and other dignitaries.

This was the first coming-of-age ceremony for an imperial prince since his father, Crown Prince Akishino, in 1985.

Born on September 6, 2006, Hisahito is the only son of Crown Prince Akishino and Crown Princess Kiko.

Now a freshman at Tsukuba University, he is pursuing biology, with a particular interest in dragonflies.

He has co-authored a study on insects found at his family’s Akasaka estate and is reportedly committed to protecting urban insect populations.

He has two older sisters: Princess Kako and former Princess Mako, who renounced her royal status after marrying a commoner.

Although Emperor Naruhito has a daughter, 23-year-old Princess Aiko, she is excluded from succession under the 1947 Imperial House Law, which reserves the throne exclusively for males.

Today, the Imperial Family has 16 adult members, but only Crown Prince Akishino and Prince Hisahito remain as young male heirs.

Former Imperial Household Agency chief Shingo Haketa told the Associated Press, “The fundamental question is not whether to allow male or female succession line but how to save the monarchy.”

Japan has had eight reigning empresses in its history, but the current law prevents women from ascending the throne.

Proposals to amend the succession system were abandoned after Hisahito’s birth.

Debate continues over whether female royals should retain their status after marriage or if distant male relatives should be adopted to maintain the lineage.