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.

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 Housing 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.”