It looms over the village, dominating the skyline, and it is this mountain, as much as anything else, that seems to have drawn the strangers to Kita Mimaki.
The first sign that something was up was mundane enough: a 15-ft high aluminium fence was suddenly erected around one of the village's vacant properties. In a Japanese community, where everybody is expected to know everybody else's business, such a drastic attempt at preserving privacy could only arouse suspicions.
Nasty rumours began circulating, so the village government hired a private detective to find out what it could about the new owners of the property, a big, two-storey house in a large plot. The rumours turned out to be true. Now everyone who watches Japanese TV has heard of Kita Mimaki, and life in the village will never be the same.
The villagers have dug a trench around the property and have put up a barbed-wire fence of their own. Specially mounted video-cameras keep it under constant surveillance, through TV monitors situated in an emergency command centre in a neighbouring building. And every day, around the clock, the property is patrolled by teams of 100 villagers, alternating by rota out of a pool of more than 2,000 volunteers. The aim of all this security is not to guard the house and its contents, but to prevent its legal owners from getting in. For, as the private detective soon discovered, the true purchaser of the property was not the lawyer named on the title deed, but the notorious religious cult, Aum Shinri Kyo.
The impact of the discovery on a place such as Kita Mimaki is hard to overestimate for, as undesirable neighbours, Aum Shinri Kyo have no equal. The cult was founded in the Eighties by a half-blind guru who calls himself Shoko Asahara, and its members embarked on a series of bizarre and outrageous crimes which for years remained unsolved by the Japanese police. As early as 1989, according to confessions by former members, they murdered a lawyer who had been acting against the cult, along with his wife and baby. A string of other killings followed, of young members who were trying to leave the cult. In 1994, seven people were killed by mysterious fumes in Matsumoto, a city close to Kita Mimaki.
The climax came on 20 March 1995 when, in an apparent attempt to hurry along the Armageddon predicted by their guru, his followers released poison nerve gas in the Tokyo subway.
It was the height of the morning rush-hour: 12 people died and more than 5,000 others were blinded or fell ill. During the raids and trials that followed (the guru, Asahara, is still being tried, in a case that could drag on for a decade), it emerged that the gas used in the two attacks was sarin, a nerve agent invented by the Nazis. The cult's many chemists had manufactured it from scratch, in a series of "facilities" alarmingly similar to the property in Kita Mimaki - isolated buildings in small villages overshadowed by another beautiful volcano, Mount Fuji.
"We know what they did in the past," says Masayoshi Mizushina, director of the anti-Aum headquarters. "What's to stop it happening again?"
When a party of about 30 Aum members turned up in Kita Mimaki early one morning last month to move into their new property, they were greeted by 500 villagers who had been summoned from their beds at 4am by the village's public address system.
"There is no other way," says Shinichi Ide, the chief of the village's volunteer fire brigade, who stands on patrol in the snow. "This is a war between us and them, because once they get inside there will be no way to stop them."
And Kita Mimaki's problem is not unique. Remarkably, four years after its uniquely horrible act of terrorism, Aum Shinri Kyo is not only still in existence, it is undergoing something of a revival. Membership is up, its businesses are flourishing, and virtually every month brings reports of new property purchases. There is an Aum website, there are Aum computer shops, and there have been unsuccessful attempts at setting up Aum tuition services and, most fantastic of all, an Aum babysitting business.
The Public Security Investigation Agency (PSIA), the closest thing Japan has to an domestic intelligence bureau, has published two reports warning of the resurgence of the cult.
"As far as we can see ," says Mr Kai, the head of the PSIA's Aum unit, "the potential danger represented by the cult hasn't diminished at all."
That Aum should even exist, let alone be in the process of expansion, may seem remarkable enough. In 1997 the cult was stripped of its tax privileges as a religious organisation; many people assumed that after it had been revealed (in sworn court testimony) as a murderous fraud, Master Asahara's followers would quietly disband. But the following year, those of the cult's leaders who had not been arrested and jailed regrouped, and former members began to return. According to estimates by the PSIA, the group now has some 700 "monks" - active resident members who leave their homes and families to devote themselves to meditation, ascetic practices and voluntary work on behalf of the cult. On top of this are 1,500 non-resident "laymen", far fewer than the 11,000 members who once followed Asahara, but enough to provide a pool of free labour for its profitable computer manufacturing business.
The cult has recently distributed flyers around Tokyo; according to the PSIA, recruiters have been active in some of Japan's most distinguished university campuses. It is in order to accommodate new members, according to the Agency, that it is acquiring property. "They look for isolation, space and mountains," says Mr Kai, of the PSIA. "High mountains have always been important to them, because of the spirits who live there."
Most creepy of all, according to the agency the cult has bought numerous houses near the Tokyo Detention Centre, where Shoko Asahara meditates in his cell, still denying the charges against him.
"They seemed abnormal," says Mr Mizushina about the cultists who turned up that January morning in an unsuccessful attempt to move into their new house. "Their eyes didn't focus. They looked as if they'd been brainwashed."
But an encounter with Aum itself produces a very different impression. It is surprisingly easy to arrange: a couple of phone calls, a list of questions, and faxed directions to a house in suburban Tokyo. Outside is a clutter of bikes and boxes; the door is opened by a smiling young man in glasses and the white outfit, a cross between martial arts clothing and pyjamas, which is the Aum uniform. Inside the house all the windows have been covered up, and weird, spacy electronic music plays constantly at low volume. In a room packed with computers, files and posters of Master Asahara, we are greeted by Hiroshi Araki, the closest thing that Aum Shinri Kyo has to an acceptable face.
In March 1995, Mr Araki was a low-ranking toiler in the cult's PR division; after the arrests of almost all the group's leaders, he suddenly found himself a senior member. He is polite, shy, articulate and entirely lacking in obvious creepiness or insincerity. For four years, he has taken on the unenviable task of fielding questions and requests from the invariably hostile Japanese media. Aum's line on the sarin attack and other killings is not to deny that they took place, but to wait and see how the trials unfold. The cult's members still carry out what they call "religious training" - Shoko Asahara's personal combination of meditation and yoga, assisted by the use of bizarre "headgear", an arrangement of wires and electrodes that is said to connect the wearer to the "brainwaves" of the guru himself.
The teachings of "the Master" are still central, and he remains the heart of the cult, although his place as leader is now occupied by his children - his 13-year-old daughter, Rika, known by the Sanskrit name Achari, and two sons, Akiteru and Gyokko, aged six and four. The Aum posters feature these two little boys sitting in the lotus position in purple pyjamas, their eyes closed in concentration. "They emit light, and when I meet them I too am illuminated," says Mr Araki. "They are very special, unique beings." He and his fellow cultists are odd, rather pitiable people. They wear strange clothes, sing strange chants, and revere a man who probably ordered the cruel deaths of 20 people. But do they really deserve to be feared as they are?
Even Mr Kai of the PSIA will go no further than to speak of a "potential" threat from the new Aum. "We've never found evidence of danger," he admits when pressed, "and we think it's impossible for them to cause the same problem again." For a start, and even if they are wrong about their phones being tapped, they are monitored constantly, undergoing frequent raids by the police, whose behaviour sometimes verges on harassment. Last November, an Aum member won compensation after an incident (captured by chance on video) in which a police officer assaulted him, and then claimed that he himself had been attacked. The failure to anticipate the sarin attack, despite numerous clues and warnings, was the Japanese police's greatest-ever humiliation, and you sense in their excessive vigilance a desire to get even.
"I've listened to what the village people have to say and I understand their concerns. But it's the police and the media who are stirring up feelings against us, making people worried," says Mr Araki. "What the police want to do is create some kind of enemy, and draw attention to it, so they can create a scapegoat for society."
The true mystery of Aum is not what its members believe, but why they choose to believe it - why, in such a sophisticated society, it draws intelligent people such as Mr Araki. Aum is not an alien, but a home-grown monster, the offspring of late-20th-century Japan. "All of us are thinking it's very strange," says Mr Arai of Kita Mimaki. "Why does Aum have such appeal for people?" That is the most difficult and important question of all.