The group has been buying up houses and other real estate across Japan to set up new offices and meeting centers in what authorities describe as an ominous effort to re-establish itself.
Police say members are once again preparing for the Armageddon they have been promised will come this year by their jailed messiah -- Shoko Asahara, who is on trial for murder in the March 21, 1995, subway gassing and other killings.
Aum's reemergence has unnerved some Japanese, such as those who live near the group's recently purchased house in Kitamimaki, a village about 90 miles northwest of Tokyo.
The spacious two-story house with white walls and black roof tiles has a parking lot for about a dozen cars and is ringed by steel fences installed by the cult.
It also is surrounded by villagers who have been keeping a 24-hour vigil for three months to make sure no one from the cult gets in.
"We will not let Aum come into our village," said Osamu Koyama, the town's mayor.
Aum was stripped of its legal status and tax privileges as a religious organization, but the government concluded it was no longer a threat and stopped short of using an anti-subversion law to ban it. So members can still assemble, spread their ideas and raise money.
Using profits from sales of computers and computer parts, for instance, the cult last year bought at least $1.65 million in real estate.
Authorities see the real estate deals as just one element in a broader and more disconcerting effort by Aum to expand in a year that is of special significance to Asahara's followers.
According to the guru's teachings, Judgment Day will come on either Sept. 2 or 3 and only cult members will survive.
Possibly in preparation, investigators say, the cult has set up several offices or meeting places around the Tokyo Detention Center, where Asahara is being held while on trial.
According to a recent report compiled by the government's Public Security Investigation Agency, Aum followers have been instructed to worship the jail as a "holy place."
"We must keep a very close watch on the group," the report warned.
Aum has significantly increased its fundraising activities.
Last year, its computer sales earned it more than $57.5 million, nearly double from the year before. And in the final four months of 1998, it earned at least $221,900 from 310 seminars attended by 7,000 people, the report said.
"I'm concerned about the situation," said Kenji Kawashima, a cult specialist who teaches at Tokyo's Keisen University. "Many young Japanese can be easily influenced by a cult with teachings that trigger fears about the turn-of-the-century catastrophe."
Aum says its recent activities are not a cause for concern.
"We are only looking for a place to live and practice," the group says on its World Wide Web page.
Police cracked down hard on Aum after the subway attack. A total of 428 cultists were arrested and the cult was stripped of its legal status as a religious group and declared bankrupt.
The cult is still a skeleton of its former self.
At its peak, Aum claimed 10,000 followers in Japan and tens of thousands more in Russia, Germany, the United States and several other countries. It now has a core of only about 500 cultists who remain at its communes, but hundreds more consider themselves members although they have not taken the final step of giving away all worldly possessions.
The trial of Asahara is expected to drag on for several more years, and most of the cult's other leaders are likely to be in prison for the foreseeable future.
But one of Asahara's closest and most charismatic disciples, Fumihiro Joyu, is expected to be freed as early as November after serving time for forgery and other minor charges from a 1990 land deal. His return could be a big boost to Aum.
While Asahara's teachings still dominate the cult's Web site, Joyu, who served as the cult's spokesman before his arrest, is also featured prominently.