By Jonathan Head
BBC correspondent in Tokyo
Crown Prince Naruhito of Japan has repeated an appeal for his wife to be allowed more freedom.
Crown Princess Masako (R) has not been seen in public for six months
In a statement on Wednesday, he apologised for distressing his parents with controversial comments made last month, but did not retract them.
The Crown Prince had charged the Imperial Household with denying Princess Masako the chance to travel and lead a more varied life.
The princess has not been seen for six months after a stress-related illness.
There was a flurry of activity around Tokyo's royal palaces on Wednesday as officials from the Imperial Household negotiated the form of words Crown Prince Naruhito would use in his latest statement over his wife.
In it he apologised for causing heartache to his parents, the Emperor and Empress.
But the heir to the Chrysanthemum throne did not budge from his core complaint - that Princess Masako has been put under unbearable strain by the requirements of royal life, and that she should be allowed greater freedom to follow her own interests.
Only males can ascend the Japanese throne
If Prince Naruhito died without a male heir, his brother, Prince Akishino, succeeds
But he has no sons either
Such bluntness from a member of Japanese royalty is unprecedented, and it has set off a public debate over how bad Princess Masako's condition must be for her husband to speak out like this.
She is reported to have had some kind of nervous breakdown.
Since her marriage 11 years ago, Princess Masako, a former career diplomat, has been under intense pressure to produce a son - only males can succeed to the throne.
But in his statement last month the Crown Prince also referred to other problems - of moves by the notoriously conservative Imperial Household to suppress her personality and career.
He now says he does not want to blame anyone, but it is clear the unhappiness at the heart of the royal family is still there.