SACHIKO OE slept all night on the floor outside her hero’s room at the Hilton, and when Peter Aerts emerged for breakfast she managed to get the 6ft 4in (1.9m) Dutchman to autograph her arm. But she was hungry for much more: what she really wanted was his blood spattered over her face.

Along with her friend Mariko, Sachiko planned her macabre strategy with obsessive precision. The 23-year-old college students had worked a month of double shifts at a hairdresser and a curry restaurant to pay way over face value for ringside seats.

With the £500 tickets in hand, they spent hours choosing clothes and applying make-up that might distract the fighters’ attention for a split second, perhaps even eliciting a treasured glance in their direction. Finally, there was the all-important digital camera to capture the image they so longed for — the gory results of a Sunday afternoon of extreme violence.

“Of course I want him to kiss me — maybe more — and I want to reach out and touch him while he is still covered in sweat,” says Sachiko. “But best would be some of his blood.”

On this occasion, Nagoya is the venue for the K1 Grand Prix — a brutal tournament that pits an international array of fighters of different martial arts styles against each other in a series of three-round brawls that regularly end in knockouts and very often medical attention. Head-butting, hitting a downed man and biting are out, but pretty much everything else comes within the K1 rules. Elsewhere in the world, this sort of spectacle attracts only the specialists — mainly middle-aged men who, in the back of their minds at least, probably fancy their own chances in the ring. In Japan, the country where this new breed of extreme fighting was invented, the audience is mainly middle-class girls.

The extreme fighting phenomenon has existed in Japan for nearly a decade, but has made its extraordinary leap into the mainstream only recently — a leap that has, to the delight of fans, brought it a deal with one of the world’s most violent fighters.

What used to be the preserve of a few thousand pay-to-view satellite customers is now a prime-time terrestrial favourite. To meet the demand for big-ticket fights, K1 has enlisted a pantheon of colourful fighters, and has secured the fighting rights of the scariest bruiser of them all. Details of the first Mike Tyson K1 fight are still being hammered out, but insiders believe that it might be billed as a Christmas special for Japanese viewers longing to see what feats of destruction “ Iron Mike” can still produce.

Such a fight would have plenty to live up to. On New Year’s Eve 2003, a fight between Akebono, the retired Hawaiian sumo yokozuna, and Bob Sapp, a bulky former American football player, attracted one of the biggest audiences in the history of Japanese television.

Japan in general takes fandom of any sort seriously: from teenagers who ape every tiny fashion gimmick of their pop idols to scooter gangs who devote their weekends to re-creating scenes from Roman Holiday. But on K1 fight day, the dirty concrete area outside the Nagoya Rainbow dome is as bizarre a sight as any you can find across the country. It is not a nice part of town, it is drizzling, and the desolation is broken only by a few grimy-looking hot-dog stands and T-shirt stalls.

Ignoring all of this, however, are thousands of Japanese women; beautifully made-up, tottering slightly on stiletto heels and wearing designer cocktail dresses that make Oscar dresses look dowdy.

There are men there too — the few hundred obvious fans of the fighting itself tend also to be the customers of the T-shirt shops. They spend their time before the fights peering at the form guides and murmuring about the relative merits of technique. A few hopefuls are there because, as one put it: “This is the biggest concentration of excited single women I am ever going to see in Nagoya.” The rest — only a modest number — have been dragged there unwillingly by girlfriends or wives, and are clearly putting on brave faces.

“It’s not that I don’t like watching sport — I love baseball and soccer — it’s just that this really is not my taste. This isn’t sport, it’s sex. Sex with blood,” mutters Tsutomu, 32, holding the hand of his 4-year-old son. “Look at my wife now, and she seems normal. Inside, she’ll change completely when she sees the muscles and the sweat. It’s crazy: later, when we get home, she’ll resent me for having a normal job.”

The K1 organisers know their market, and know exactly how to maximise the pre-fight tension — both sporting and sexual. Fireworks explode within the dome, vast mechanical pillars rise suggestively from the floor and giant screens descend from the ceiling to show the past exploits of the fighters — slow-motion shots as a nose is smashed by a flying kick or a man knocked cold by a knee to the face. Now out of their seats and screaming, the women are treated to a few moments of ecstasy as their heroes emerge from strategically placed doors around the auditorium and stride towards the ring through a sea of desperately groping — and exquisitely manicured — hands.