Tokyo, Sept. 7 -- The 19-year-old, nephew of Emperor Naruhito, is now second in line to the Chrysanthemum Throne.

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.

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

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.

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 ...