Why Japan's Prince Hisahito Is Called 'Dragonfly Prince'

Prince Hisahito, nephew of Emperor Naruhito, has received his black silk and lacquer crown to formally mark his entry into adulthood. The 19-year-old is the first male in Japan's imperial family in 40 years to reach the milestone.

Despite Emperor Naruhito having a daughter, Princess Aiko, she cannot inherit the throne because of a 19th-century rule that abolished female succession.

Hisahito, also known as "Dragonfly Prince," is second in line to the Chrysanthemum Throne after his father, Crown Prince Akishino.

He is likely to become emperor, but with almost no other male heirs in the family, Japan may eventually have to reconsider its male-only succession rule. Currently, the law allows only men to ascend the throne. 

Why is Prince Hisahito called Dragonfly Prince?

Prince Hisahito is currently studying biology at Tsukuba University near Tokyo. During a press conference in March, he said he hoped to focus his studies on dragonflies and other insects, including ways to protect bug populations in urban areas, according to CNN.

He is fascinated by dragonflies and has even co-authored an academic paper on a survey of the insects on his Akasaka estate in Tokyo. 

What is Japan's rule that only allows a male heir?

Japan has a long history of male emperors, but female succession was permitted in the past. There have been eight female emperors, including Gosakuramachi, who ruled from 1762 to 1770. However, none of these women produced heirs during their reigns.

In 1889, during the Meiji period, Japan created its prewar Constitution. For the first time, succession was legally restricted to men. After World War II, in 1947, Japan created the Imperial House Law under the new constitution. This law continued the male-only rule, which stipulates that only men can inherit the Chrysanthemum Throne.

Today, the Imperial Family counts 16 adult members, but only Crown Prince Akishino and Prince Hisahito remain as young male heirs. The rule could change in the future to allow women to become emperors.