AN hour before midnight on a frigid winter night in the Japan Alps, it appears that the men perched atop the blazing wooden tower are being grilled alive like human yakitori. Below them, a battle rages with fists, elbows and flaming torches in what looks like a bizarre, medieval skirmish. This apparent attempt at human immolation is taking place in scenic Nozawa Onsen spa, set in a valley a few hours train ride east of Tokyo. The Nozawa Onsen, population about 5,200, near Matsumoto City, site of the 1998 Winter Olympics, is designated as an Olympic training village. The spa has been popular since the feudal lord of Iiyama opened it to the public in the 17th century, and skiing was introduced from Austria 75 years ago. In the attractive, traditional community two-and three-storey natural wood buildings with upswept tile-roofs line narrow streets. Behind split door curtains in tiny tatami-mat restaurants, waitresses in kimonos serve noodles with seaweed and snow-white slices of pressed fish cake. Sliding doors open briefly on the street to reveal bare bodies steeping in public hot baths. Of Japan's 650 ski resorts, including 107 in this prefecture (Nagano), Nozawa Onsen claims the country's finest facilities. Tonight, though, Nozawa Onsen is not a ski resort but a traditional mountain community following its own customs. The village has celebrated Doso-jin Hi-matsuri, one of Japan's major fire festivals, every January 15 since 1839. The festival, which starts at 8.30pm sharp, is held to eliminate evil spirits, pray for a good harvest and honour all first sons born that year. The logic of the festivities escapes foreign visitors, but the excitement is as real as a run down one of Mount Kenashi's more challenging slopes. An air of exhilaration and anticipation of the night's fiery affair charges the crowded streets. Colourful wooden gods in paper costumes are set out before open temples, and souvenir shops sell blank-eyed, legless daruma good luck dolls from the size of a fist to bigger than a beach ball. I'm told Daruma was a god who meditated in a cave so long his legs fell off. Those receiving these round, vermilion dolls as gifts fill in one pupil. When the wish comes true, they fill in the other. Last year's darumas burn in bonfires in the village square. New dolls adorn village trees like red Christmas baubles. Six frail towers, poles about 20 metres high draped with a hooped skirt of kami paper strips written in Japanese script, stand around the village square. Each family that had a son born the previous year makes one of these very expensive towers which will be burned as part of the festival. As a visiting gaijin (foreigner), I am invited to a private party held by a family which has sponsored one of the flimsy first-son towers. The couple's cute, chubby-faced boy howls at meeting the funny stranger. In the large tatami straw mat restaurant, scores of guests squat at low tables bearing a feast of sushi, chicken tempura, rice, pickles and other delicacies. Family members scurry around with large bottles of beer and kettles of warmed sake, filling cups and glasses. At one end of the room, an impromptu choir of jolly, flush-faced men sing ''Sake is my Friend,'' a long, multi-versed paean to the rice wine accompanied by hand clapping and jolly, flush-faced drunkenness. As I depart, bowing thank-yous at the door, the 100 or so Japanese guests applaud me, although all I have done is eat their food and drink their sake. Well fed and fuelled, I return to the darkened streets and the build-up to the festival. Along the narrow lanes, roving revellers in head-bands like bandages with red Japanese lettering reel by, swigging from litre bottles of icy sake which they pass around to shopkeepers and bystanders. Swaying and stumbling, the meandering minstrels bear flaming straw torches the size of apprentice sumo wrestlers, a half-dozen carrying each one like a huge battering-ram. Then more groups come by, all parading through the streets for hours working themselves up for the big event. Many of the celebrants are becoming as legless as the daruma dolls. Few foreigners walk these snowy streets, despite the easy accessibility to Tokyo, and the accommodation here and in nearby towns. But in the sub-zero chill, perhaps 8,000 excited Japanese skiers and locals jam the town square, stamping their feet for warmth. In the centre, floodlights illuminate a three-storey (about 10-metre) tower of sticks and branches standing like a gargantuan sheaf of wheat on a low, slippery mound. Where the firewood tower spreads out slightly at the top, all of the town's 42-year-old men, perhaps 20 to 30 of them, sit jammed together in a row. Clad in workman-blue overalls and hard hats, they wave Japanese-style globe lanterns, clap white-gloved hands and sing. Below them, all of Nozawa Onsen's 25-year-olds, the Men of the Year, defend the base of the tower. The rest of the townsmen, the attackers, cluster around a giant bonfire blazing a few hundred feet away. First the village elders, then the children light torches and attack the kindling tower. This part is quite ritualised as the defenders part to let them through, then beat out the fires with their tree branches. The preliminaries go on for about half an hour with no damage done to the tower. Then, at some unseen signal, like at the start of a sumo match, a dozen of the young attackers light torches made of bundles of sticks from the bonfire and charge the tower. The defenders beat them back with kicks and punches, shoving them down the slippery hill, thrashing out the flames with pine branches. From where I stand back in the crowd, the fierce, more-than-mock battle seems dangerous, with fists, elbows and blazing torches shoved in combatants' faces. The attackers charge in packs, sometimes breaking through to light the tower, but the defenders beat back their foes and brush out the flames. The potential victims with the front row balcony view of the struggle sing, clap, swig sake, wave and mock the attackers, throwing more bundles of sticks down, as though taunting them with more ammunition. ''The defenders are very strong this year,'' a Japanese fire festival aficionado tells me. Gradually, though, the more numerous attackers make headway, breaking through the ranks to set the tower aflame. The zealous crowd roars whenever the tower catches fire, and now glowing cinders and sparks rise into the black night as flames lick up around the human sacrifices who chant even more vigorously. For hours the battle rages and it seems as if the men on the tower will be roasted alive. Now, the attackers seem to be making headway, breaking through the ranks more often and getting up against the tower with their flaming torches. The small fires they set last longer, and sometimes flames lick up under the participants on top who seem unfazed by it all. Meanwhile, the attackers push the main bonfire closer and closer, to about four metres from the tower which is a pillar of flame. Then, half-hidden in the huge billows of smoke, the would-be victims slip away down a ladder at the back. By midnight, the tower blazes like a steam locomotive's boiler, with flames and burning branches rising hundreds of feet in the air, and warming those of us standing far back, despite the freezing temperatures. Next morning, only a pile of ash and cinders remain on the snowy square. Nozawa Onsen's first-born sons have been dutifully honoured. And all of its 42-year-olds will live to be 43.