They are grainy, indistinct photographs, but for a Japan on the edge of recession they are more than enough: a pricey Mexican dinner, a plate of rare black truffles and a bowl of shark-fin soup have unleashed an unprecedented media broadside against the future Empress of Japan.

After years of careful, respectful restraint, the Japanese press have turned on Crown Princess Masako: sympathy has turned to condemnation and tolerance has become attack.

Princess Masako's offences are trifling by the standards of European royal households. She has taken the occasional evening off and left her six-year-old daughter with a babysitter for a night with her friends. She has dined once or twice with acquaintances at expensive French and Chinese restaurants, ridden a horse and shopped in central Tokyo. She has eaten dinners that a salaryman might sign off without a glance and her household costs amount to only £1.5 million a year. Yet, by the self-consciously austere standards of the Japanese Imperial Family, Masako has taken luxury too far.

In the space of only a few weeks the woman in whom clinical depression was diagnosed four years ago has gone from victim to fair game. Where once the media accepted her need to recuperate from an “adjustment disorder”, it now attacks her for wasting public funds. The general public remains on Masako's side but why, scream the tabloid magazines, does she still shy from official public duties when she has been spotted having dinner with friends?

To many outside Japan the Princess is the ultimate broken butterfly — the Harvard-educated commoner who married into the straitjacket of Imperial family life and whose spirit was crushed by a ruthless bureaucracy. To some in Japan, though, Masako is very nearly a failure: she is the princess who did not manage to produce a male heir and who has been too ill to perform her public duties since 2004.

In a country that cherishes above all the spirit of gaman — perseverance — the unspecified mental illness from which she is suffering is merely an obstacle she is too weak to overcome.

The Japanese press has held fire on Crown Princess Masako for years but her illness is poorly understood and recent signs of recovery have been taken as malingering.

The chief problem, sources close to the Crown Prince told The Times, is that depression as an illness is very badly understood by normal Japanese. “People see it, mistakenly, as something you simply have to fight hard to overcome, so any failure to do so is seen as a failure of the spirit.”

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