The writer has just returned from assignment in Japan. However formidable Japan's economy may appear to competitors overseas, some very real problems for the Japanese themselves are clouding up fast on the horizon.
No one is more aware of this than Japanese leaders charged with trying to figure out where their nation will be in the year 2000 and beyond.
The aging of the population and the need to ''unlock'' the rigid Japanese educational system are topics that come up time and again in conversations. Solution of these problems, experts agree, may profoundly affect the structure of Japanese society, especially relations between the old and young.
''Twenty years ago,'' Saburo Okita says, ''only 5 percent of the Japanese population was over 65. Now the percentage is 9.6 percent. By the year 2000 it will reach 20 percent.''
Dr. Okita, head of the Institute for Domestic and International Policy Studies in Tokyo, chaired a long-term outlook committee set up by the Japanese government in 1981 to study the ''nation's long-term perspectives into the 21st century.''
The speed with which the Japanese population is aging, Dr. Okita says, is ''three times as fast as in Europe'' and faster than the United States. The financial burden of supporting a much larger number of retired people will be enormous, says Prof. Kazutoshi Koshiro of Yokohama University.
''In 1980,'' he said, ''only 3.8 percent of Japan's gross national product (GNP, or total income) went for old-age pensions. By the year 2010 more than 13 percent of GNP will be swallowed up by pensions.''
Who will pay? Primarily workers and employers through payroll taxes levied on wages and salaries, as in the United States and Western Europe.
Currently, says Dr. Koshiro, 10.5 percent of all wages are contributed - 5.25 percent each by workers and employers, slightly lower than the US payroll levy.
''Over the next 15 years,'' he says, ''I expect growing resistance by younger people at this increasing rate of redistribution of income.''
So far, says Satoshi Inaba, director of the Employment Policy Division of the Ministry of Labor, tension between young and old is not a problem. ''But,'' he adds, ''it could become unbearable in the future, unless ways are found to revise the pension system.''
Among changes now being explored by the Ministry of Welfare:
* Increasing payroll taxes and reducing the growth of benefits. (This formula was adopted for the US social security system by Congress and the White House.)
* Postponing eligibility, which now stands at age 60 for a partial pension and 65 for full benefits.
Already, experts say, many Japanese companies are encouraging older workers to remain on the job, both to reduce the pension burden and to pour more taxes into the system.
Keeping older people at work, however, reduces the number of job openings for young workers at the same time that robotics threatens to reduce job opportunities overall.
Explorations on revising the pension system so far remain just that - explorations. ''No one,'' says Prof. Michio Nagai, chairman of the Social Policy Council of the Japanese government, ''can give you an answer on how to solve this problem.''
''The attitude of young people,'' he adds, ''is a major question mark. At least there is a basic respect for the elderly ingrained in Japanese.''
A rapid growth of juvenile delinquency, meanwhile, alarms adult Japanese. ''One-fifth of all Japanese crime is committed by youngsters under 15,'' Dr. Nagai says.
In part, at least, juvenile crime appears to reflect tensions bred by the intense competition among young Japanese to excel at school, as a steppingstone toward successful careers.
Mothers, especially, prod their youngsters to do well at school - a phenomenon colloquially described in Japanese as the ''mama monster.''
More broadly, questions arise about the efficacy of Japanese education, at a time when Japan increasingly strives toward new frontiers of technology.
''Japan has a much shorter history in science than the United States or Europe,'' says computer scientist Kazuhiro Fuchi. ''Graduates in new fields of science and technology still are a smaller proportion of the population than in the US.''
''The Japanese education system is good up to a point,'' says Tadashi Sasaki, chairman of the Japan Committee for Economic Development. ''It turns out uniform quality manpower, very good for making technology saleable in quality consumer products.''
But this system, he adds, does not ''sufficiently develop the individual'' in ways that lead to scientific or technical breakthroughs,'' fields where the US retains a lead.
Japan's curriculum, says Dr. Fuchi, ''reflects the Japanese ability to produce (people of) great competence, but not genius types.''
''Japan's industrial competitive power will be very strong in the 1980s,'' comments Nobuyuki Fukuda, president of Tsukuba University. ''But in the 1990s?''
He shrugs. ''The potential power of US science and technology is tremendous, '' partly because of the US educational system, partly because of immense research funds poured into American space and military endeavor.
''Japan's task,'' says Dr. Fukuda, ''is somehow to unlock the educational system, to allow more flexibility and creativity as young people develop.''