College senior Takashi Yamamoto thought he would get the jump on his classmates when he began offering his services to major Japanese banks and stockbrokerage firms last spring, months ahead of the yearly mass job hunt now in full swing here.

Despite his enterprising spirit, however, Yamamoto, 23, was politely but firmly turned away first by one company and then another. Under more normal circumstances, the bright, bespectacled youth would have been snapped up long ago.

But this year times are tough. "At first, I thought I was just plain unlucky, but then I realized that things are really bleak for everybody," he said, speaking of the downturn in Japan's economy that has forced companies all over the country to cut back drastically on job recruitment.

Yamamoto and many of the 400,000 new job-seekers like him, who will be graduating from Japanese universities next March, are not the only ones fighting a case of the unemployment blues. Thousands of older Japanese workers are being tapped by employers for early retirement in retrenchment efforts reflecting a drop in Japan's export business and a prolonged slump in its domestic economy.

Widespread layoffs and outright firings still are rare in Japan's parternalistic system of lifetime employment, where companies have traditionally cosseted employes in a cradle-to-grave fashion. The system has freed Japanese workers, in most industries, from any worries of job security and has helped ensure a fierce company loyalty that has formed a cornerstone of the country's economic empire.

Now, however, there are signs that the system may be fraying. Corporate executives, labor union leaders and government officials here are concerned that the constricting job market could put strains on the country's remarkably smooth relations between management and workers and, ultimately, impair Japan's high rates of overall industrial productivity.

In June, unemployment hit the highest level since 1955, with 1.4 million people out of work, and more joblessness is expected in the months ahead.

At roughly 2.5 percent of the workforce, Japanese unemployment may seem enviably low by American standards, although some private economists here say that the actual figure might be as high as 6 percent if government statisticians applied a more lenient yardstick. The pool of lifetime workers, they point out, harbors large numbers of employes who are kept on payrolls with little or no productive functions to perform.

Japan's employment headaches have been compounded by the blistering advance in recent years of automation in factories and offices that has reduced job opportunities for a growing labor pool at a time when the country's economy is expanding at only about 4 percent a year, or less that half the rate of the halcyon, high-growth days of the 1960s and early 1970s.

Adding to the pressures is the gradual structural transition of Japan's economy from steel, shipbuilding, petrochemicals, and other labor-intensive areas that formed the backbone of postwar industry. The country's new, knowledge-intensive industries--computers, telecommunications and precision machine tools, among others--simply do not require as large a labor pool.

According to Yasuo Kuwabara, a senior researcher at the Japan Institute of Labor, the Japanese have stunned themselves with their own virtuosity in churning out the industrial robots and labor-saving electronic gadgetry that has aroused the admiration and envy of other advanced industrial economies.

"Originally, we thought that this new technology would actually create new jobs," he said, "but, judging from recent trends, I guess we may have been wrong."

At the same time, today's longer Japanese lifespan, among the longest in the world, has helped create a growing army of older workers, many of whom now want to stay on the job beyond the mandatory retirement age--between 55 and 60 at most companies. This has put new strains on corporate coffers because of Japan's seniority-based system in which workers are paid higher wages according to their number of years with the company. It also has made it more difficult for employers to make room for younger, and less expensive, workers.

A growing number of career-minded Japanese women also have contributed to the job crunch. While the workplace in Japan remains a bastion of male supremacy, Kuwabara said, "the old pattern was for young women to get a job and work for a few years. Then they got married, raised a family and disappeared from the job market forever. Now, many are inclined to just stay put."

According to the Nippon Recruit Center, a large, Tokyo-based employment agency, the number of new jobs being offered by major companies listed on Japanese stock exchanges has dropped by 12 percent this year after hitting a postwar peak only two years ago. The job outlook is more dismal in Japan's vast small business sector, which has been hardest hit by the current recession.

Labor analysts say that, statistically, there still are one and a half jobs in the market for each individual wanting to work. But when openings for waitresses, truckdrivers, nightwatchmen and other menial tasks are excluded, there are considerably fewer opportunities for today's increasingly well-educated, occupation-oriented Japanese youth.

No one here is seriously anticipating a return to the high levels of business failures and unemployment immediately after World War II that helped spark widespread strikes and social unrest. But the analysts point out that the country's apparently flawless sense of social cohesion and its rockbottom crime rates have been based, to an important degree, on workers' ability to benefit from an expanding economic pie that has kept jobs plentiful and expectations on the upswing.

"Until recently, labor unions, management and government officials could afford to be very flexible in dealing with new economic realities," said Ryuichi Aritoshi of the Ministry of Labor's Employment Police Brueau. "But now, the pace of change is so rapid that, if we fail to adapt quickly enough, the consequences could be quite severe."