Japan's troubled prince regrets travelling alone

TOKYO (Reuters) - Japan's Crown Prince Naruhito said on Wednesday he regretted that his wife, who has been suffering from a mental illness for years, would be unable to accompany him on an official trip to Brazil this month.

He was speaking to reporters days after marking the 15th anniversary of his marriage to Crown Princess Masako, 44, a former diplomat educated at Harvard and Oxford who has made only limited public appearances over the past four years.

"Masako is also extremely grateful for the invitation from the Brazilian government," Naruhito said at the Togu Palace in central Tokyo, which he shares with his wife and their six-year-old daughter, Aiko. "Both she and I are disappointed that she is unable to go."

Naruhito said the Brazil visit, which celebrates the 100th anniversary of the arrival of the first Japanese immigrants, involved a lot of travel and public events.

"In consultation with doctors, we made an overall decision that I should go alone," he said, adding he hoped for understanding.

Naruhito, 48, is also set to travel to Spain alone in July.

Masako, whose father was also a diplomat and who spent much of her life before marriage outside Japan, has spoken in the past of the difficulty of adjusting to the cloistered life of the palace and the lack of foreign travel.

"If there is something she might be able to cope with physically, it would be good if she could go," Naruhito said when asked about the possibility of Masako returning to public duties abroad. "Or if it is something that might contribute to her recovery."

In 2006 the royal couple raised eyebrows by paying a two-week private visit to Holland, an unusual move for an heir to the Chrysanthemum throne.

The emperor, Naruhito's father, said at the time he and his wife had never taken an overseas trip in a private capacity -- a comment some Japanese media saw as veiled criticism of the holiday.