The prince, who is the only son of Prince Akishino and Princess Kiko, turns 10 on Tuesday.
The milestone comes at a crucial time for the Japanese royal family.
In rare video address to the public this month, Emperor Akihito, 82, said he worried age might make it difficult for him to fully carry out his duties.
Under Japan´s male-only inheritance laws, Hisahito is third in line to the throne after his father and uncle, Crown Prince Naruhito, 56. Hisahito is the first male child born into the Japanese royal family in more than four decades.
There have been discussions about amending the laws to allow women to inherit the throne, but traditionalists oppose this move.