SITTING down to lunch one day earlier this week, an official of Japan's National Press Club half-joked that this country feels like it is falling apart.
After yesterday's events in Yokohama, that analysis seems a notch less funny. More than 300 people at three railway stations in the city sought medical treatment after complaining of a foul odor and throat irritation, apparently caused by chemical fumes.
Already edgy Japanese police, fire, and military personnel scrambled to the scene in Yokohama, a city about 30 miles south of Tokyo. Officials quickly addressed the immediate question: Was it sarin?
Sarin is the nerve gas that killed 12 people and injured thousands in the Tokyo subway system on March 20, an act of anonymous, indiscriminate terrorism that has galvanized this country ever since. Officials and doctors say that whatever caused people to cough and gag in Yokohama yesterday was something different. It was certainly less dangerous -- hospitals say most people were only lightly injured yesterday and nobody is reported to have died.
Nonetheless, the Yokohama incident will add to the sense of social unease that has been the talk of Japan for the past month. Even if there is no chemical connection to the sarin attack, most people speculated about possible links.
Atsayuki Sassa, a former director general of the Japanese Cabinet's security-affairs office, noted that the Japanese parliament yesterday passed a law making the possession or use of sarin a criminal offense. He suggested that the events in Yokohama were intended to be ''a kind of warning or signal'' to the government on the day of the law's passage.
Mr. Sassa is among the many Japanese who suspect that the religious sect Aum Shinri Kyo, or Supreme Truth, is responsible for the sarin attack. A long-time investigator of subversive movements in Japan, Sassa says Aum has been mounting a ''revolution without ideology'' in Japan. ''I think [their] fundamental philosophy is nihilistic or anarchistic,'' he says of the group. ''They have started their Armageddon against us.''
Police have arrested dozens of Aum members on a variety of charges -- ranging from traffic violations to kidnapping -- but have not accused the group of actually committing the sarin subway attack. The police have said they want to question Aum's leader, Shoko Asahara, but he is in hiding, and police apparently have been unable to find him.
The local media, meanwhile, have issued a daily stream of reports detailing Aum's accumulation of large amounts of chemicals and other industrial equipment that group members say they acquired in order to be self-sufficient and prepare for an impending apocalypse. Government investigators have said that some of these materials can be used to make sarin.
Other reports, sourced to the police, have linked the group to the manufacture of guns and the acquisition of larger-scale weapons, allegations its members deny.
Even more troubling to many Japanese is the kind of people that Aum has attracted: students and graduates of top-ranked universities, at least one former member of an organized-crime-group, and even some members of Japan's military. An Aum magazine this month published a detailed account of the first raid that investigators mounted on the group's main facility at a village called Kamikuishiki two days after the sarin attack. The report was so accurate, one military analyst told a television interviewer, that it had to have been written with privileged information.
But the sarin incident and the emergence of Aum are not the only things troubling the Japanese consciousness. On March 30, an assassin came very close to killing the chief of Japan's National Police Agency as he left for work. Even the Kobe earthquake on Jan. 17 has added to the malaise, because the devastation showed that high-tech engineering could not protect people to the degree its proponents had hoped.
''All of these incidents have caused people to feel unrest and worry about the future of the society,'' says Masaharu Gotoda, one of the country's most senior and respected politicians. ''The Japanese people are now faced with unrest, in terms of politics, economy, and the society. The current task therefore is how to remove people's unrest.''
''The ominous cloud of uncertainty over the sarin poisoning incident,'' said the Asahi newspaper in an editorial yesterday, ''instantly spread and now hangs over the entire Japanese archipelago. The cloud shows no signs of clearing up and rather seems to be getting thicker.''
That uncertainty accounts for the massive security measures taken in Tokyo last weekend, after Mr. Asahara issued warnings about a calamity striking the capital. Nothing untoward took place, but huge department stores shut their doors and plainclothes police were evident at several popular thoroughfares. News reports said pedestrian traffic in some parts of Tokyo was half of what it usually is.
Last night, after searching the train and the underground concourse in Yokohama where people were affected by the fumes, police said they had found no receptacle that might have held noxious chemicals .
Two weeks before the Tokyo sarin attack, on March 6, passengers on a late train in Yokohama complained of bad odors, sore throats, and eye irritation. Almost a dozen people sought medical help. There again, police found no source.