In 1991, economists were predicting that Japan would overtake the United States as the world’s largest economy by 2010. In fact, Japan’s economy remains the same size it was then: a gross domestic product of $5.7 trillion at current exchange rates. During the same period, the United States economy doubled in size to $14.7 trillion, and this year China overtook Japan to become the world’s No. 2 economy.

China has so thoroughly eclipsed Japan that few American intellectuals seem to bother with Japan now, and once crowded Japanese-language classes at American universities have emptied. Even Clyde V. Prestowitz, a former Reagan administration trade negotiator whose writings in the 1980s about Japan’s threat to the United States once stirred alarm in Washington, said he was now studying Chinese. “I hardly go to Japan anymore,” Mr. Prestowitz said.

The decline has been painful for the Japanese, with companies and individuals like Masato having lost the equivalent of trillions of dollars in the stock market, which is now just a quarter of its value in 1989, and in real estate, where the average price of a home is the same as it was in 1983. And the future looks even bleaker, as Japan faces the world’s largest government debt  around 200 percent of gross domestic product  a shrinking population and rising rates of poverty and suicide.

But perhaps the most noticeable impact here has been Japan’s crisis of confidence. Just two decades ago, this was a vibrant nation filled with energy and ambition, proud to the point of arrogance and eager to create a new economic order in Asia based on the yen. Today, those high-flying ambitions have been shelved, replaced by weariness and fear of the future, and an almost stifling air of resignation. Japan seems to have pulled into a shell, content to accept its slow fade from the global stage.

Its once voracious manufacturers now seem prepared to surrender industry after industry to hungry South Korean and Chinese rivals. Japanese consumers, who once flew by the planeload on flashy shopping trips to Manhattan and Paris, stay home more often now, saving their money for an uncertain future or setting new trends in frugality with discount brands like Uniqlo.

As living standards in this still wealthy nation slowly erode, a new frugality is apparent among a generation of young Japanese, who have known nothing but economic stagnation and deflation. They refuse to buy big-ticket items like cars or televisions, and fewer choose to study abroad in America.

Japan’s loss of gumption is most visible among its young men, who are widely derided as “herbivores” for lacking their elders’ willingness to toil for endless hours at the office, or even to succeed in romance, which many here blame, only half jokingly, for their country’s shrinking birthrate. “The Japanese used to be called economic animals,” said Mitsuo Ohashi, former chief executive officer of the chemicals giant Showa Denko. “But somewhere along the way, Japan lost its animal spirits.”