An Australian journalist has refused to apologise over his book on Japanese Crown Princess Masako.
The princess now only makes limited appearances in public
The Japanese government said Ben Hills' book contains groundless claims and insults the royal family, and wants an apology and corrections.
Mr Hills said he had nothing to apologise for and accused officials of trying to suppress his book.
He said the only person who deserved an apology was Crown Princess Masako for her treatment by the royal family.
Princess Masako was a diplomat who spoke several languages and travelled the world before her 1993 marriage to Crown Prince Naruhito, heir to the Chrysanthemum Throne.
After she joined the Imperial family she began to suffer from a stress-related illness. She is now rarely seen in public and carries out few official duties.
Many blame her ill health on the pressure to produce a male heir, the BBC's Chris Hogg in Tokyo says.
The Japanese throne was facing a succession crisis until Crown Prince Naruhito's younger brother, Prince Akishino and his wife, had a baby boy last September.
Ben Hills said he had interviewed more than 60 Japanese, US and English sources for his unauthorised biography, Princess Masako - Prisoner of the Chrysanthemum Throne.
The sources included her former colleagues and those of her husband, many of whom, Mr Hills said, had never given interviews before.
The Crown Prince and Princess have a daughter but no sons
But Japan's foreign ministry said the book contains "disrespectful descriptions, distortions of facts and judgemental assertions with audacious conjectures and coarse logic".
The ministry said it had sent official letters to Mr Hills and his publisher, Random House, seeking an apology and unspecified "prompt measures".
Mr Hills accused the government of wanting to thwart the publication of a Japanese edition, which is due to be published in a few weeks time.
"I regard this as an attempt by the Japanese government to suppress and censor my book and I think it is absolutely outrageous," he was quoted by Japan's Kyodo news agency as saying.
"There is nothing to apologise for. In fact, there is only one person in this saga that deserves an apology and that's Princess Masako.
"I think the Kunaicho (Imperial Household Agency) should apologise to her for bullying her into a state of nervous breakdown."
Random House declined to comment on the controversy, but said it was standing by the author.