Japanese princess starts school

Princess Aiko is the daughter of Japan's crown prince

Princess Aiko, a potential heir to the Japanese throne, has started kindergarten in Tokyo.

The four-year-old daughter of Crown Prince Naruhito and his wife Princess Masako went to a beginning of term ceremony at Gakushuin Kindergarten.

Princess Aiko attended the ceremony with her parents and 50 of her future classmates, and later met her teachers, Japan's Kyodo news agency reported.

The future of the monarchy is a major issue in Japan.

At the moment, only men are allowed to ascend the Japanese throne, but there is no male heir to follow Crown Prince Naruhito or his brother, Prince Akishino.

Prime Minister Junichiro Koizumi had been paving the way for new legislation allowing women to ascend the throne.

But the move appears to be on hold following the news that Prince Akishino's wife, Princess Kiko, is pregnant, raising the possibility that she could give birth to a boy.

The strain caused by the succession debate is said to have affected Princess Masako's health. She has been seen in public only rarely in the past two years and is said to be suffering from stress.

But she accompanied Princess Aiko, who was smartly outfitted in a navy blue skirt and blazer and a matching hat, as she set off for her first day at nursery school.

The Japanese school year begins in April.