Prince Hisahito of Akishino is the youngest child of Emperor Naruhito and Empress Masako of Japan. He is the first male heir to the Chrysanthemum Throne in over 40 years and is currently third in line to the throne. He was born on September 6,
From Wikipedia
Prince Hisahito of Akishino is a member of the Imperial House of Japan. He is the youngest child and only son of Crown Prince Fumihito and Crown Princess Kiko, and the nephew of Emperor Naruhito. He is second in the line of succession to the Japanese throne behind his father.