It is, to say the least, a hit with some improbable elements. An ornamental section of Shall We Dance?, for example, was filmed in, of all places, Blackpool. Its director, Masayuki Suo, began his career in the porn sector. His motive for making the film was to get Japan's middle-aged "salary men" back into cinema houses, but he has unexpectedly encouraged a whole bunch of Americans to tag along too.
As well as winning all 13 national film awards in Japan, it is the sixth most successful foreign-language film at the American box office. And Suo has been profusely thanked by the Japanese Amateur Dancing Association for rescuing ballroom dancing in Japan from ridicule.
The film tells of Sugiyama, a straitlaced middle-aged office worker who docilely assents to the established order of overwork, crippling mortgage and dull daily commute. Waiting one night for the train to train him back to his wife and daughter in the suburbs after a hard day's tedium, Sugiyama spots a glacially beautiful woman staring mournfully out of a fourth-floor window. Like a stricken damsel in a fairy-tale, she is there each time he waits for his train.
One evening he sheds a couple of layers of thickly encrusted inhibition and tries to find out who she is - only to discover to his horror that she gives lessons in a ballroom dancing school, Japan's rough cultural equivalent of the one-on-one sex line: as absurd as it is embarrassing.
Several more layers of inhibition have to go before he enlists for weekly lessons, only to discover that the object of his obsession will not be his teacher. He goes back every week, slowly overcoming his clumsiness among a colourful ensemble - a lumpy nymphomaniac, a periwigged rumba god from his office.
His wife interprets his late nights and furtiveness as evidence of an affair, and sets a private dick on him. In fact, when he does extend a dinner invitation to Mai, the woman in the window, who wears the psychological scars of tumbling in a prestigious Blackpool dance competition, she spurns him. This goads him to step up his dancing, which he now starts to relish for its own sake, which in turn defrosts Mai.
Shall We Dance? reads as an essay in how not to be Japanese, a manual for shunning formality.
Suo himself has clearly shunned formality: when I met him in London, he was wearing a mile-wide pinstripe suit by Yamamoto that even his most flamboyant ballroom dancers would rather die than wear. In an intimidating break with tradition, he also filmed the interview on a minuscule broadcast- standard Sony videocam.
So, I ask, is it about unlearning Japanese ritual? "That's one way of putting it," he says. "In Japan we are brought up not to bring out our emotions. We go through life suppressing, almost killing our feelings in order to conform to conventions of society.
"What I wanted to say was, let's not do this any more. Let's appreciate and enjoy our own life. But that doesn't necessarily mean let's become American."
The film's success in America proves that while aimed at the kind of lapsed cinema-goers embodied by the main character, it has a wider message. Suo's take on this is that "a film which I created for middle-aged Japanese people happened to contain what the Americans viewed as a treatment of the midlife crisis".
He claims he was also thanked by Americans "for making a film without sex and violence". They should have seen his first film, then.
Suo is not the only Japanese director to learn his craft in skin flicks. Born in Tokyo in 1956, brought up in Kawasaki, he studied French at university, after which office life of the kind endured by Sugiyama beckoned. "I appreciated that once I'd got into that kind of world, that's all I would be able to do."
He nursed an ambition to direct, but with the collapse of the studio system in Japan there is no fixed way of going about it. So Suo simply approached his favourite director and asked to be his assistant.
That director was Takahashi Bannei, who makes erotic "pink" films in the independent sector. Bannei didn't make In The Realm of the Senses, the most well-travelled example of the genre, but was best man to Magisa Oshima, who did.
Though to westerners it looks a bizarre entree for an aspiring director, porn in Japan is probably more mainstream and less artistically laughable than ballroom dancing. "In Europe, porno films aren't even on the map," says Suo. "But in Japan they are very much a part of film life. Of course these were erotic films, but Bannei was exploring the depth of humanity through sex."
Suo's first film was duly as pink as they get. But that didn't stop it from being a homage to the pre-eminent Japanese director.
"I wanted to express my absolute love for Ozu, the master," he says. "Ozu's Late Spring ends with the father sending his daughter off to marry and join a different household, and my film imagines what it would be like if she joined a household where people were a bit sexually perverted."
What would Soho's dirty-mac crowd make of it? They may get the chance to find out. Its Japanese title is Strange Family, but an English version is in the pipeline called The Daughter-In-Law.
Pornography served its purpose: Suo got a toehold in the business, and his next two more films threw sideways glances at more mainstream areas of Japanese culture. In Manic Zen (1989), a rock singer becomes a nominate monk in order to take over the Buddhist temple run by his father. Sumo Do, Sumo Don't (1992) tells of a bunch of skinny undergraduates who join a struggling sumo club to get credits towards their degree. "In the course of training in sumo they realise that life has a lot more possibilities than they thought it had to offer."
In the course of learning to dance, Sugiyama comes to much the same conclusion. In order to see the unfunny side of ballroom dancing, Suo underwent much the same regime as his hero. "To write the screenplay I danced for six months once a week and racked up 20 hours of dance practice. Before I danced I had no idea how enjoyable it was going to be." And like his hero, he fell in love with Mai: after the film wrapped he married Tamiyo Kusakari, a leading Japanese ballerina who plays her in her acting debut.
Filming outside Japan was another novelty, though he seems not to have found Blackpool as alien or - his word - "weird" as ballroom. "Wherever you look there's only old people," he says. "Time has stopped. Even though I'm not even vaguely English, I found it very nostalgic."