World Behind My Wall

As of Friday, Prince Hisahito, the Japanese imperial family's first male heir born in 41 years, weighed 13.6 kilograms and was 94 centimeters tall, the Imperial Household Agency said.

Under Japan's male-only succession law, Prince Hisahito is third in line to the Chrysanthemum Throne behind Crown Prince Naruhito, 49, Emperor Akihito's eldest son, and Prince Akishino, 43, the emperor's second son.

Prince Hisahito enjoys lively activities, like riding a tricycle from his elder sister Princess Kako, playing ball and chasing, and has gradually become able to eat and change clothes by himself, according to the agency.

His parents affectionately call him "Yuyu," "Yu-chan" and "Hisahito- kun," it said.

The boy uses polite language, possibly following the example of family members and employees of the agency, it said.