This may make you choke on your sushi...

Does one of the host nations of the World Cup bring to mind geishas and duty-bound businessmen? Cut the cliché, says Ayako Yoshino.

The world's greatest sporting carnival has kicked off again. Brace yourselves for a flood of goals and a torrent of cliche. Even now, the television commentators are practising their "German efficiencies", juggling their "Brazilian flairs", and drilling their "Nigerian athleticisms".

Of course, the host countries can expect their fair share of stereotyping, and Japan, where England play all of their group matches, will be the focus of particularly loving attention from the British media. It would be a wonderful opportunity to correct some stereotypes, but if past media coverage can be taken as a guide, it is probably not too pessimistic to expect numerous beautiful images of Kyoto's Golden Pavilion and Mount Fuji set against disappointingly shallow chatter about a group-oriented, homogeneous, hierarchical and highly technological society governed by concepts of shame, duty and discipline. If we are really lucky, we might even get the odd reference to "traditionally submissive Japanese women".

There will be nothing new in that. Casual stereotyping of Japan has long been a staple of the British media. It may come as a surprise to some, but the bizarre gameshow Endurance has probably been more widely disseminated in this country through Clive James's programmes than it ever was in Japan, where it was about as mainstream as topless darts was in Britain. The 1980s song "Turning Japanese" - already a fixture in the World Cup build-up - sounds puzzlingly Chinese to the Japanese ear.

But what is the real story? Ron Atkinson and Terry Venables might not notice it, but English football is visiting a country that is in the midst of the most fundamental changes not only to its economy and politics, which have been rocked since the collapse of the "bubble" stock markets of the 1980s, but to its basic ideas of itself. A new breed of Japanese academics is presenting an unsettling self-portrait to the nation, and the first targets to be attacked have been postwar theorists who described the country as having a uniquely homogeneous and group-oriented culture.

Kosaku Yoshino, associate professor of sociology at Tokyo University and author of Cultural Nationalism in Contemporary Japan , has made a study of "Nihonjinron", theories of Japanese distinctiveness, which he says became popular in postwar Japan after the traumatic experiences of devastating military defeat, vicious self-recrimination by Japanese in the immediate postwar years, rapid and enforced Americanisation, and subsequent breakneck economic growth. These theories, which often emanated from mainstream academics and were massively popular in the 1970s and 1980s, could border on the absurd: the idea that Japan's rice-growing tradition meant that the Japanese were uniquely family-oriented compared with the West's "wheat-growers", as Eiichiro Ishida argued in 1969, or the apparently contradictory proposition that the West's "hunting traditions" made for a highly analytical mode of communication as opposed to the Japanese rice-grower's emphasis on "feelings of consideration, gratitude, encouragement and sympathy, which are unnecessary for hunting", as Yuji Aida stated in 1972. There is also the rather unsettling case of The Japanese and the Jews , the bestselling book of all genres in 1970, contrasting the nomadic self-oriented Jews with the cooperative Japanese. Its author, Isaiah BenDasan, claimed to be Jewish but is widely thought to have been a well-known Japanese social critic.

"The first thing to understand about these ideas is that they go well beyond the facts. They are a faith system, which had more to do with delineating what it meant to be Japanese so it was safe for the country to absorb foreign cultural elements. Nihonjinron was an attempt to define a supposedly homogeneous Japan against an imagined homogeneous West," Yoshino explains. Many of these theories were exclusively concerned with a binary, oppositional relationship with the West, often feeding off mistaken western theorising about Japan and excluding the exploration of relationships and ties with other cultures. Japan was therefore seen as unique.

Of course, the reality never quite fitted these imaginings. Yoshino points out that, while Nihonjinron theorists celebrated Japan's "classless" society, hundreds of strikes were reported every year. Japan is also more ethnically diverse than is widely understood. The average British traveller will find it difficult to distinguish Japan's main ethnic groups, but figures in 1998 showed that there were about 640,000 Koreans in the country, 260,000 Chinese and about the same number of Brazilians, of whom large numbers were Japanese-Brazilians. There were also hundreds of thousands of Peruvians, Filipinos, Thais, Indians, Middle East nationals and westerners. Although foreigners make up a relatively small 1.2 per cent of the Japanese population, some communities found themselves with up to 14 per cent of non-Japanese inhabitants by the mid-1980s.

Many of these groups are becoming increasingly assertive. Physical differences are impossible to determine, even for the Japanese, but ethnic Koreans are now rapidly taking up their original names and rebuilding their own cultural identity. There are 86 Korean schools and colleges in the country. Japan's two main minority groups with Japanese nationality - the Ainu and Okinawans - are showing a similar resurgence.

And it is not just ethnic minorities who are challenging received ideas of Japanese homogeneousness. Japan's leading feminist, Tokyo University professor Chizuko Ueno, says: "Nationalism and sexism often go hand in hand because women are often, in fast-changing societies, made to represent culture and tradition. While men quickly adopt western suits, women are often made to remain in the traditional clothes. That's why some reactionaries attack Japanese women as the very people who destroy Japanese tradition."

It would be a major surprise if this summer's World Cup coverage did not feature a good number of that highly endangered species, the geisha. But while white-faced, tightly bound girls may remain a predominant image of Japanese womanhood abroad, Ueno's data paints a radically different picture.

The figures show that housewives are now in a minority in Japan. She says:

"Japan now has one of the lowest birthrates in the developed world, and the reason for that is simply because so many Japanese women choose not to get married. It is so visible. Even if they get married, they tend to do so at much later age than they used to. Sexual liberation has happened in Japan as well. At the moment, 25 per cent of the first-born of newlyweds are conceived before marriage. Long past are the days that being single meant no sex life. Submissive and chaste Japanese women no longer exist or, more precisely, they never really existed."

Falling birthrates combined with economic depression have meant a major restructuring for Japan's university sector. While this has generally been characterised by a shift from non-vocational to vocational education, with subjects such as law and information technology prospering at the expense of humanities subjects, the shake-up has also directed new interest at traditionally neglected areas such as gender and applied social sciences. Even in a bastion of an old academic order such as Japanese history, Yoshihiko Amino, a medieval specialist, has detected a new wind blowing. Early this year, a major academic publisher began publishing a series of studies of the history and politics of the Japanese emperor system. "The very idea of the publication of such works would have been inconceivable in the past," says Amino, who became one of Japan's most controversial academics by confronting many of the assumptions of Nihonjinron and describing medieval Japan as having diverse cultures and modes of production.

Fresh thinking has not been confined to ivory towers. Amino's work provided inspiration to the makers of Princess Mononoke , a 1997 historical fantasy that became Japan's highest grossing domestic film. NHK, Japan's more stern equivalent of the BBC, last year broadcast a television drama series set in Okinawa, emphasising that island's distinctive culture. But more momentous was a primetime documentary in the same year dealing with the roots of the Japanese people and blowing apart ideas of their racial and cultural homogeneousness. Millions of viewers of Japanese: Long Journey were treated to an account of a country with racial origins in numerous farming and hunter-gathering groups across Siberia, Malaysia, Indonesia, China and Korea, an account not dissimilar to the established view of Britain's varied racial and cultural heritage. The effect of this kind of fresh thinking has been profound, Yoshino says: "It is no longer rare to hear the Japanese referring to themselves as a mongrel nation."

Not all debate in Japan in recent years has been along such progressive lines. Reactionary nationalism has prospered among some parts of the population during the economic depression of the past decade. The present prime minister, Junichiro Koizumi, has sometimes pandered to such sentiment, and Tokyo's highly nationalistic governor, Shintaro Ishihara, has made a political career out of attacking foreigners. However, whatever some older Japanese people might tell you, one thing that Japan is certainly not at the moment is a uniquely "homogeneous" or "harmonious" society.

Ayako Yoshino is taking a PhD on cultural nationalism in Edwardian England at Girton College, Cambridge.