On paper at least, the life of Hiroshi Araki looks like something out of Franz Kafka. Whenever he steps outside his flat, at any time of the day or night, men with clipboards make a note of the time he leaves, who he is with and which way he is going. They are there, rain or shine, 24 hours a day, never fewer than three of them and sometimes a dozen.
Some are elderly retirees, local volunteers with time on their hands. Some wear uniforms, and some are plain-clothes men with policemen's eyes. Once a month they raid his flat and those of his friends, and confiscate files and computer disks. "The average person who experienced this kind of thing would have a nervous breakdown, but it's been going on for seven years so we've almost got used to it," says Mr Araki. "At least they've stopped following me."
Mr Araki is a skinny, earnest young man with a liking for yoga and meditation; he has committed no crime and threatens none. So why are the forces of justice in Japan treating him like an active member of a terrorist cell? The answer lies with the yoga group of which Mr Araki is a member.
Today it calls itself Aleph, and its teachings and practices are indistinguishable from the harmless mumbo-jumbo purveyed by any number of neo-hippy groups all over the world. But until two years ago it was known by a different name: Aum Shinri Kyo – apocalyptic religious cult, perpetrator of mass murder, and the least desirable next door neighbours in Japan.
Founded in the 1980s by a half-blind guru known as Shoko Asahara, the cult embarked on a series of bizarre crimes that culminated in the world's first ever terrorist use of chemical weapons. On 20 March 1995, in an apparent attempt to hurry along the Armageddon predicted by their guru, Asahara's followers released home-made sarin nerve gas in the Tokyo subway.
Twelve people died, and more than 5,000 were blinded, choked and nauseated. A series of arrests followed and so far a number of Aum members have received death sentences for their part in the killings (the trial of the guru continues). The cult was declared bankrupt and, having been so devastatingly unmasked, it was assumed that it would quietly disband. But, to the irritation of the Japanese police and the alarm of many Japanese, it survives.
According to Mr Araki, who acts as the group's spokesman, it has 520 resident "monks" and 600 non-resident "laymen" – far fewer than the 11,000 who once followed Asahara.
Whenever they are asked, officials insist Aleph remains "dangerous". Even the US State Department includes it on its list of international terrorist groups. But despite the monthly search warrants, constant surveillance and a fervent desire to catch Aleph doing something, no one can explain what the danger is.
Aleph, both in person and on its website (http://english.aleph.to) has repeatedly apologised for the horrors of 1995. It has promised to pay 4bn yen (£22m) in compensation to the victims and their families; so far Y300m has been handed over.
"Mobilising every possible criminal legal code and interpreting these laws as liberally as possible, they tried to criminalise many petty offences on an unprecedented scale," wrote Akira Fukuda, a criminal law professor and one of the few to express disquiet about official treatment of the group.
The truth is that the notion of a potentially resurgent Aum justifies police budgets and staff levels that otherwise would be hard to justify. The failure to prevent the subway attack remains the Japanese police's greatest ever humiliation and it is difficult not see an element of revenge in the petty abuses they dish out on the cult's successors. "It's the police and the mass media who are stirring up feelings against us," said Mr Araki. "What the police want to do is create an enemy and draw attention to it so they can create a scapegoat for society."