So, will the world end tomorrow?

The Earth is about to be zapped by deadly waves, according to members of Japan's Panawave cult. But even if doomsday doesn't happen, should we be worried by the nation's proliferation of bizarre sects?

Fukui Prefecture, Japan. Just days to Armageddon, but the members of Panawave still find time to wash their underwear. Two of the white-robed cultists scrub clothes in basins, while their colleagues drape their trademark Persil-white sheets across trees and bushes. Ignore the Ku Klux Klan-style garb and it could be an encampment of particularly fastidious New Age ramblers.

Fukui Prefecture, Japan. Just days to Armageddon, but the members of Panawave still find time to wash their underwear. Two of the white-robed cultists scrub clothes in basins, while their colleagues drape their trademark Persil-white sheets across trees and bushes. Ignore the Ku Klux Klan-style garb and it could be an encampment of particularly fastidious New Age ramblers.

"Is the end of the world still on schedule?" shouts someone from the pack of reporters besieging the group's base in this remote mountainous area on the Sea of Japan coast, earning a muffled expletive from behind a white mask.

The cult, which believes that an undiscovered planet is set to knock the Earth off its axis tomorrow, has perhaps understandably let the laundry pile up. Having wandered around remote roads in central Japan in their caravan of white vans and SUVs for months in blissful anonymity, the group was instantly catapulted to national fame when a television film crew caught up with them a fortnight ago.

Open-mouthed viewers saw reporters scuffling with men apparently dressed in sheets, who shouted that the broadcasting equipment was giving them cancer. Later, crews were greeted by cultists carrying giant mirrors to deflect the "electromagnetic waves" from cameras.

Visitors to the Panawave site (www. panawave.gr.jp) learnt that the world will end on 15 May with a series of cataclysmic events, including earthquakes and tidal waves provoked by gravity from the unseen planet.

With the war in Iraq winding down, Japanese politics stuck in apparently endless stalemate and Sars so far miraculously bypassing the country, Panawave's antics were an oasis in a media drought. The press pack chased the group across half a dozen prefectures as city after city passed resolutions telling them to go back to where they came from.

Asked why they covered crash barriers and trees with sheets wherever they stopped, the cultists at first patiently explained to smirking reporters that it was to protect them from microwave attack by left-wing guerillas. They said that the group's guru, Yuko Chino, had contracted cancer from these attacks, and that they were wandering around in search of countryside free from electricity pylons where she couldrecover.

By the time the Panawavists realised that these explanations were making things worse, they were already the most famous weirdos in the country. Although they are so far guilty of little more than being a nuisance, twitchy local leaders across central Japan hounded them back to their base in Fukui last weekend.

The badge of notoriety was firmly stamped after Prime Minister Junichiro Koizumi said that he found it difficult to understand "why people believe in things said by such a group". When the newspapers revealed a Panawave plot to kidnap a cute sea-lion called Tamachan, who has captured Japan's heart since he wandered off course into a Tokyo river, the cultists became public enemy No 1.

A decade ago, Panawave might have swum harmlessly beneath the media radar, one of thousands of mostly benign pseudo-religions that have blossomed in post-war Japan since the collapse of the imperial system.

But the country's tolerant attitude to kooky cults was changed forever in May 1995 when another doomsday group, Aum Shinrikyo, gassed Tokyo's underground transport system, killing 12 and injuring over 5,000 people. Led by the toxic figure of Shoko Asahara (whose trial for the attacks is now reaching its final stages), Aum Shinrikyo built up a huge stockpile of chemical weapons, plotted to overthrow the government and tortured, kidnapped and killed its enemies for years under the noses of the authorities, before finally carrying out the worst single incident of terrorism on Japanese soil.

The investigative reporter Shoko Egawa, who first exposed Aum and was almost murdered by the group as a result, is among those who fear that a similar cult could emerge at any time. "The problem is that Japan is breeding more of these groups," she says. "The reason why the government doesn't crack down on them hard is because the [ruling] Liberal Democratic Party gets donations from all sorts of religious organisations. And they are currently in coalition with New Komeito [a political front for the Buddhist organisation Soka Gakkai], so there is a lot of resistance to the strict regulation of religions."

The result is that Japan lives with its thousands of religions, while potentially incubating the next disaster. The Honohana cult, for example, led by the multimillionaire Hogen Fukunaga, recently milked millions of dollars from wealthy people by persuading them that he could detect illnesses from the soles of their feet.

The question being asked, then, in homes and bars across Japan, is: are Panawave members harmless hippies or something more sinister? Certainly, they appear to be unlikely inheritors to the legacy of Aum Shinrikyo, whose articulate members came from the cream of Japan's universities. Even as their crimes publicly unravelled, the Aum leaders often ran verbal rings around their opponents in televised confrontations.

By contrast, none of the Panawavists seem especially bright, and far from embracing the media age, the cult's members do not even watch television, fleeing from "radiation-emitting" cameras whenever possible. Few seem capable of winning the world over with a witty soundbite. "You look but cannot see. Communists are attacking us. Prepare yourself!" one cultist told bemused television reporters on Monday.

Where comparison to more dangerous cults is spot on, though, is in the odd, insular world that the Panawavists have created for themselves, under the guidance of yet another charismatic leader. Chino, their ailing 69-year-old guru and a former English teacher, endured a troubled childhood in a poor area of Osaka, culminating in attempted suicide and a sham marriage, before she slowly built up a nucleus of followers to her mixture of Buddhism, Christianity and science fiction.

In the 1980s, the "beautiful and elegant" Chino became obsessed with the possibility of a Soviet invasion of Japan. She persuaded her disciples, who are officially numbered in the thousands, to construct the cult's facilities in remote Fukui Prefecture 16 years ago to protect them from electromagnetic waves. Followers say that as she got older, the guru became increasingly reclusive and ill.

"When the electromagnetic waves started, Chino would get sicker," one Panawave member said this week. "It's become difficult to spread the word of Chino, so most of our studies are now done among ourselves." Chino's last public statement, issued on 5 May, said that the end would come "when electromagnetic waves strike the Japanese archipelago and the delicate gravitational balance between the Andromeda nebula and other nebulas is altered."

Despite the looming doomsday, however, Fukui residents report nothing odd from their years living next-door to their kooky neighbours, unlike the locals around Aum facilities, some of whom were gassed in Sarin leaks. "They look weird, but they never did anything to me," says 70-year-old Miyoko Miyashita, as she bundles up vegetables on her allotment near the Panawave camp. "They seem to go away for long periods, then come back. To be honest, I hardly even noticed them any more until you media people came round."

The president of the local neighborhood association, Kiyoshi Maeda, is equally laid back. "They need watching but essentially they're not dangerous," he says. "The only things I'm worried about are their numbers increasing and their cars blocking the traffic. They have to get permission from us now to move, but they're mostly co-operative."

Local residents near another of the cult's facilities in Yamanashi Prefecture, where Panawave members are building beehive-like structures to protect themselves, also say that, while creepy, the group is guilty of little except bad architecture.

Still, the group is clearly serious about preparing for the end of the world. Officials who inspected the Yamanashi site last week found a Noah's Ark-like compound of dogs, cats and pigs, and even an iguana. Moreover, the history of cults cheated out of their Day of Reckoning is not pretty. Some have been known to artificially hasten their end, such as the 39 members of Heaven's Gate who committed group suicide at Rancho Santa Fe, California in 1997. The Heaven's Gate followers were plunged into despair when the spaceship that they thought trailed the comet Hale-Bopp, which was supposed to transport them to a higher state of existence, left them behind.

Despite the dangers of a similar tragedy, the police in Fukui are determined to keep the cultists barricaded in their camp until the media and other onlookers go away and 15 May passes. A squad of ultra-rightists, unhappy at what they said was the way Panawave was "giving anti-communism a bad name" and anxious to quiz the cultists on their opinion about the Emperor, were politely but firmly turned back. Reporters are barred from entering the Panawave compound.

Are the authorities worried about what the cultists will do as doomsday approaches? "You'll have to ask them that question," says Koji Fukuda of the South Fukui City Police. "For us, it's just a public-order problem."

"You won't let me ask them," I point out.

"Well, they hate the media and that's not my fault. Anyway, you'll only stir things up."

"Have you prepared yourself for the end of the world?" I ask.

"It doesn't matter what happens," he laughs, "I'll still be standing here come Thursday."