Princess Aiko has been absent from school since leaving early on Tuesday
Japan's Princess Aiko has been off school since early this week after complaining of being bullied, a royal household official has said.
The princess, eight, had come home from school in a state of anxiety and saying she had stomach pains, he said.
It was found she and other students in her class had been "treated harshly" by boys in another class, he added.
Princess Aiko, daughter of Crown Prince Naruhito and Princess Masako, attends Gakushuin Primary School in Tokyo.
The royal spokesman, Issei Nomura, did not give details of when the princess, who is a granddaughter of Emperor Akihito, was expected to return to lessons.
Princess Aiko is the only child of Crown Prince Naruhito and Princess Masako
She left early on Tuesday and has not been back since.
Mr Nomura said the palace had asked the school to address the matter and had been given permission to publicise the princess's situation, the Japanese news agency Kyodo reports.
A school director told reporters the princess had been frightened on Tuesday when a boy had run out of a classroom, which "must have reminded her of the rowdy behaviour of several boys in the past, who may have thrown things and made her uneasy", Kyodo says.
Princess Masako has rarely been seen in public for several years as a consequence of a nervous condition attributed to the stress of life in the royal household.