AMSTERDAM- On Tuesday, Japan’s best-known prisoner -- Her Imperial Highness Crown Princess Masako – will after 11 years of relative isolation join her husband Crown Prince Naruhito’s at the coronation of Willem-Alexander in the Netherlands.

What would be routine protocol for most members of imperial and royal families will, for Masako, 49, represent a huge move outside the narrow borders imposed on her by a diagnosis in 2004 of “stress-induced adjustment disorder." Many have compared the emotionally ill Crown Princess with the tragedy of Princess Diana, and go so far as to say Lady Di was luckier because she died young.

The drama of watching Masako Owada’s transition over the years from life-loving, cosmopolitan Tokyoite – who in June 1993 wed Japan’s Crown Prince after seven years of hesitation – to prisoner of her own anxieties cannot be overstated: it is as if one were witness to a cruel, slow form of suffocation.

The charming, gracious daughter of a Japanese diplomat, Masako grew up in Moscow and New York, and graduated summa cum laude in economics from Harvard. As a young diplomat herself, she studied international relations at Oxford.

What Masako didn’t fully realize or perhaps didn’t want to face when she married was just how unprepared she was for the burden and claustrophobic rules of the role she was taking on, and the combined expectations of her husband, in-laws, a rigid imperial household, and Japanese society that she would bear a son.

Members of Japan‘s "Chrysanthemum Throne" don’t fuel the tabloids the way Britain’s Windsors do, and after Emperor Hirohito had to give up semidivine status after World War II, they have behaved with a certain amount of humility.

There’s no show here, albeit a great deal of ceremony. A Princess Di-style rebellion would be unthinkable. Divorce is a possibility, for as long as Masako isn’t Empress. But the loss of face would be unbearable, and might even lead her father to seppuku – committing suicide by ritual disembowelment. So the woman who was Masako Owada is effectively serving a lifetime sentence in a golden high-security palace.

Nobody knows when exactly the pressure started to make her ill. In December 1999 Masako lost a first child; the second, who was born in December 2001, is an adorable girl named Aiko. Her only drawback was that she isn’t a boy and hence won’t be able to succeed her father on the throne.

Masako’s “failure” to produce a male heir resulted in a slow swell of negative rumors out of the imperial household picked up by the media: she was leading the Crown Prince around by his nose, neglecting her duties. The fact that she spoke longer than the Crown Prince did at the press conference announcing their engagement suddenly took on negative connotations, pointing supposedly to a lack of humility on her part.

It is said that 13 members of the Crown Prince’s household quit within five years because of Masako’s domineering nature in the privacy of their home, and her refusal to meet her full share of public obligations. What was also considered her extravagance – a penchant for Bulgari jewelry, expensive ski trips -- also came in for a roasting.

Still: the couple went on official trips abroad, mainly to the Middle East. Masako’s sense of duty was still winning out over her anxiety. But then in 2002 her depression or panic attacks apparently started to alarm the imperial family, and she was seen less and less often on official occasions. In December 2003, she came down with shingles and spent weeks in hospital. In July 2004 the palace announced an official diagnosis of “stress-induced adjustment disorder.”

After nearly 10 years, during which regularly on her birthday in December the palace makes an announcement about how she’s doing – that despite the upbeat phrasing never sounds very hopeful – some specialists believe she may have dysthemia, or chronic depression. The princess is apparently treated with psychotropic drugs in “low dosages,” the principle therapy being to keep official appearances to a minimum so as to minimize her stress.

It would appear that Crown Prince Naruhito, 53, is unconditionally devoted to his wife. It is said that when he asked her to marry him he swore that he would protect her from the pressures of her new position. He has several times asked the public and the media for their patience and empathy.

Despite the appeals, it would appear that in Japan, Masako can’t do anything right anymore. In the whole of 2012 she only left the palace 30 times and never went beyond Tokyo city borders. In late March, a blogger claimed that on an incognito outing with her husband and child the family was in the train station when a man around 60 yelled at her that she was just a “malingerer stealing our tax money, get out of the imperial family!”

Some no longer hesitate to advise the Crown Prince to seek a divorce. Or as one hypocrite wrote, to give up the throne and "make his wife happier" – after all, his younger brother Akishino, 48, is already making many official appearances in lieu of their father Emperor Akihito who will be 80 this year, and he has not only two daughters but the all-important son.

If Masako is coming to the Netherlands for the coronation, it would seem to be because – since an invitation to visit from Queen Beatrix in 2006 that she and the Crown Prince accepted – she harbors a certain affection for the Dutch royal family and wants to see people she considers friends.