By Caroline Wyatt
BBC News, Paris
A dozen or so Japanese tourists a year have to be repatriated from the French capital, after falling prey to what's become known as "Paris syndrome".
The reality of Paris does not always live up to the dream
That is what some polite Japanese tourists suffer when they discover that Parisians can be rude or the city does not meet their expectations.
The experience can apparently be too stressful for some and they suffer a psychiatric breakdown.
Around a million Japanese travel to France every year.
Many of the visitors come with a deeply romantic vision of Paris - the cobbled streets, as seen in the film Amelie, the beauty of French women or the high culture and art at the Louvre.
The reality can come as a shock.
An encounter with a rude taxi driver, or a Parisian waiter who shouts at customers who cannot speak fluent French, might be laughed off by those from other Western cultures.
But for the Japanese - used to a more polite and helpful society in which voices are rarely raised in anger - the experience of their dream city turning into a nightmare can simply be too much.
This year alone, the Japanese embassy in Paris has had to repatriate four people with a doctor or nurse on board the plane to help them get over the shock.
They were suffering from "Paris syndrome".
An encounter with a rude Parisian can be a shocking experience
It was a Japanese psychiatrist working in France, Professor Hiroaki Ota, who first identified the syndrome some 20 years ago.
On average, up to 12 Japanese tourists a year fall victim to it, mainly women in their 30s with high expectations of what may be their first trip abroad.
The Japanese embassy has a 24-hour hotline for those suffering from severe culture shock, and can help find hospital treatment for anyone in need.
However, the only permanent cure is to go back to Japan - never to return to Paris.