“The restaurant industry here is so linked to the state of the economy, and that’s why we’re seeing this decline,” said Munenori Hotta, a food service industry expert at Miyagi University in Japan. “In this climate, even top restaurants are having to moderate their prices to keep attracting customers,” he said.

Japan’s dining-out boom had its roots in the 1970s and 1980s, as incomes grew and rural populations flocked to big cities. So-called family restaurants brought cheap, Western-style food to the masses flourished in that era. So did American fast-food chains, which were considered novel at the time. Kentucky Fried Chicken opened its first restaurant here in 1970, followed by McDonald’s in 1971.

At the other end of the price range, a new generation of wealthy Japanese savored imported French wines at lavish restaurants. By 1986, there were 503,088 restaurants across Japan, according to records from the Internal Affairs Ministry. That was nearly double the number from 15 years earlier  and was more restaurants than now operate in the United States, which has more than twice the population of Japan.

After the bubble burst in 1990, new low-cost restaurant chains that offered pizzas for as little as 400 yen, or $4.86, started to spread across Japan, and restaurateurs spoke with alarm of ready-made, convenience-store meals that were siphoning off sales.

In the depths of the slump, in 1995, Mr. Tanaka started a company based on serving quality sushi on the cheap.

His idea of using conveyor belts to offer diners a steady stream of sushi on small plates was not a new one; an Osaka-based entrepreneur invented such a system in the late 1950s. But Mr. Tanaka set out to undercut his rivals with deft automation, an investment in information technology, some creativity and an almost extreme devotion to cost-efficiency. In Japan, where labor costs are high, that meant running his restaurants with as few workers as possible.

Instead of placing supervisors at each restaurant, Kura set up central control centers with video links to the stores. At these centers, a small group of managers watch for everything from wayward tuna slices to outdated posters on restaurant walls.