Japanese Crown Prince Akishino has criticized the media coverage of his daughter Mako’s marriage and slammed Internet commenters for writing “particularly terrible” things about her and her husband, in unusually candid comments from a member of Japan’s royal family.

Akishino, who is the younger brother of Emperor Naruhito, said slander, “whether it is in a magazine or online,” can hurt people or even cause them to take their own lives, and “is not something that should be permitted.”

In October, Princess Mako married a commoner, Kei Komuro, who she met in college. The couple became engaged four years ago, but the marriage was delayed when their relationship became embroiled in controversy after news surfaced about a financial dispute involving Komuro’s mother.

The couple faced a torrent of criticism online about their relationship, and protesters gathered to oppose their marriage, including on their wedding day. Mako experienced symptoms of post-traumatic stress disorder in the wake of the barrage of negative commentary, her doctors said.

Akishino’s remarks, which were made last week at an annual news conference held to mark his 56th birthday, were published in footage released Tuesday.

He said that while some opinions about the couple in the press “should be carefully listened to,” others were “fabrications,” and some comments online were “particularly terrible.” The royal family should develop protocols to combat coverage it viewed as incorrect in the future, he added.

The couple’s wedding last month took place without pomp or circumstance, with the duo addressing the public in a simple statement after a staff member of the Imperial Household Agency submitted their paperwork at the registry office.

Akishino said his daughter’s PTSD prevented the couple from having a more open exchange in that moment. “Rather than a one-way conference, I wanted it to be two-way,” he said, but “she could have had an anxiety attack during the news conference so it would have been difficult.”

The two have now moved to the United States, where Komuro practices law, to start a new life.

When women in Japan’s royal family marry commoners, they must abdicate their royal titles — a rule that does not apply to men and that has drawn criticism from overseas.

Women who choose to take this step traditionally receive around 150 million yen ($1.3 million) from taxpayers as compensation — however, Mako declined the payment, and she and her husband said they would pay for the news conference that followed their marriage out of their own pocket.

During his birthday news conference, Akishino said it was ultimately his decision to forgo traditional wedding ceremonies for his daughter, but lamented that this “gave an impression that imperial ceremonies and rituals are very trivial.”

“I think marriage is a personal matter, and four years had passed” since the announcement of the former princess’s relationship with Komuro, he said. If the “public” were given priority, “she wouldn’t be able to marry for 10 or even 20 years,” he added.

He said he had wished Mako and her husband well in their new life. “They made the decision to live in the U.S., so I think that is what’s best for the two of them.”

Michelle Ye Hee Lee and Julia Mio Inuma contributed to this report.

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