TOKYO, Sept 6, (AP): Japan’s Prince Hisahito is the first male royal to reach adulthood in 40 years. He could also be the last. The elaborate palace rituals to formally recognize Hisahito as an adult on Saturday are a reminder of the bleak outlook for the world's oldest monarchy. Much of this comes down to its male-only succession policy and dwindling numbers.

Hisahito is second in line to the Chrysanthemum Throne and is likely to become emperor one day. After him, however, there is nobody left, leaving the Imperial family with a dilemma over whether they should reverse a 19th century ruling that abolished female succession. A freshman at Tsukuba University near Tokyo, Hisahito studies biology and enjoys playing badminton.

He is especially devoted to dragonflies and has co-authored an academic paper on a survey of the insects on the grounds of his Akasaka estate in Tokyo. In his debut news conference in March, the prince said he hopes to focus his studies on dragonflies and other insects, including ways to protect bug populations in urban areas.

Hisahito was born on Sept. 6, 2006, and is the only son of Crown Prince Akishino, the heir to the throne, and his wife, Crown Princess Kiko. He has two older sisters, the popular Princess Kako and former Princess Mako, whose marriage to a nonroyal required her to abandon her royal status. Hisahito’s coming-of-age rituals fall a year after he turned 18, reaching legal adulthood, because he wanted to concentrate on college entrance exams.

Hisahito is the nephew of Emperor Naruhito, who has one child, a daughter, Princess Aiko. Hisahito's father, Akishino, the Emperor's younger brother, was the last male to reach adulthood in the family, in 1985. Hisahito is the youngest of the 16-member all-adult Imperial Family. He and his father are the only two male heirs who are younger than Naruhito. Prince Hitachi, former Emperor Akihito's younger brother, is third in line to the throne but is already 89.

The shortage of male successors is a serious concern for the monarchy, which historians say has lasted for 1,500 years. The issue reflects Japan’s rapidly aging and shrinking population. Japan traditionally had male emperors, but female succession was permitted. There have been eight female emperors, including the most recent Gosakuramachi who ruled from 1762 to 1770. None of them, however, produced an heir during their reign.