Hiro Matsumoto opened his first sushi restaurant in New York nine years ago despite the advice of friends who believed Americans would never eat raw fish.

His Takesushi restaurant flourished, attracting Americans and members of the growing Japanese business community in New York. It did so well, in fact, that Matsumoto soon started four more successful Japanese restaurants in New York to complement his existing wholesale fish business.

His next move was back to Tokyo, where he opened a Takesushi branch to capitalize both on the name recognition among visiting Americans who were introduced to the restaurant in New York and to provide a ready supply of first-rate chefs for his U.S. enterprises.

Now Matsumota has expanded into downtown Washington, where Takesushi has become the latest hangout of Japanese businessmen, bankers and diplomats who yearn for the unique Japanese specialties of sushi (raw fish served with cold, vinegared rice, sometimes wrapped in thin sheets of seaweed) or sashimi (raw fish dipped in soy sauce laced with a hot, green horseradish called wasabi).

"That's an ideal place for a congenial lunch with friends," said Toshio Asakai, who runs the Washington office of the Bank of Tokyo.

Despite what appears to be the simplicity of the meal, a sushi lunch is no bargain; a meal for two of sashimi, sushi and a small bowl of clear soup, washed down with a bit of warm saki and some green tea, can cost at least $60. But, the Japanese say, it is far cheaper here than in Tokyo.

So on an average day, Takesushi is likely to serve Washington representatives of some of the largest Japanese businesses; diplomats from the embassy and Americans who represent them here. Bank of Tokyo representatives were at one table recently, a Japanese diplomat was dining with two men from the Japan Automobile Manufacturers Association at another and two Japanese newspapermen were at a third. An American diplomat formerly stationed in Japan sat at the sushi bar, reading his paper as he ate.

When Prime Minister Yasuhiro Nakasone visited here in mid-January, Takesushi sent out boxed sushi dinners each night to the 50 Japanese reporters covering the trip.

Takesushi has joined close to a dozen other Japanese sushi restaurants that have sprung up in the Washington area during the past 18 months. The Ginza, a block away from Takesushi, is a favorite of some National Geographic photographers who like to talk about far-away places while nibbling their sushi.

Before that, Washington was a sushi wasteland, especially compared with New York, where the sushi boom started in the mid-1970s. Now there is hardly a block in midtown Manhattan without its sushi restaurant or Japanese noodle shop.

Sushi-Ko, on Wisconsin Avenue in upper Georgetown, became Washington's first sushi restaurant when it opened in the late-1970s. It quickly gained loyal customers starting with diplomats from the Japanese Embassy located on Massachusetts Avenue, a short drive away. At about the same time, Silver Spring's old standby for Japanese food, Sakura Palace, added a sushi bar.

The sushi boomlet coincided with the Orientalization of Washington dining. Trendy, high-priced Chinese restaurants are replacing French and Italian ones as the hot new favorites of the expense account crowd. They are following the trail blazed by the opening of Germaine's, a pan-Asian restaurant whose menu swings through the best of Chinese, Vietnamese, Thai and Korean cuisines.

Thus, Sichuan Pavilion, which advertises chefs from Chungking and spices imported specially from mainland China, began serving recently at the K Street location formerly occupied by one of Washington's finest and most expensive French restaurants, the Pavilion.

Another up-market Chinese restaurant with close ties to the People's Republic of China, Sichuan Garden, opened on 19th Street--across from the traditional lunching spot for lawyers, the Palm. Despite the competition, Sichuan Garden quickly became an "in" place, with three-day waits for luncheon reservations, because of its subtly spiced food and beautiful presentation.

Its connection with the Mainland Chinese government, however, places it off limits for Taiwan's chief representative in the United States, Dr. Frederick Chien, who said he has heard of the restaurant but dares not go there. Instead, he showed up for the debut of Mr. K's, which is owned by an old friend. Two stone lions guard its entrance on the western edge of downtown's restaurant row.

These types of restaurants have spelled the end of the inexpensive Chinese lunch at most downtown spots, with the major exception of Chinatown. At Sichuan Garden, for instance, lunch for two without drinks usually costs more than $40.

For the Japanese, a sushi lunch follows a prescribed ritual. First comes a plate of sashimi--plain raw fish, usually tuna, squid, a whitefish such as flounder served on a plate with a cone of horseradish called wasabi and an attractively arranged mound of shredded white radish. Placing the fish and garnishes on a sashimi plate is an artful exercise, with the colors and textures expected to form a pleasing pattern. Warm saki--rice wine--generally is sipped with sashimi.

After that appetizer, the serious business of a sushi lunch begins. Sushi is accompanied by green tea, followed by a bowl of either clear or bean soup.

It is possible to order a sushi platter, with the various types picked by the chef and sit at a table. But a true aficionado sits at the sushi bar--where be can see the day's offerings and watch the chef work--and orders each item individually. Some people have been known to wait as long as an hour to get a choice seat at the sushi bar so they can get a good view of the sushi chef's artistry .

Masuo Kawasaki, the chef at Takesushi, is an acknowledged master. He formerly was sushi chef at the Kyubei Restaurant in the New Otani Hotel, a favorite Tokyo dining spot for Japanese.

"The chef is most important to this kind of business," said Matsumoto, Takesushi's owner. He often goes into partnership with chefs in order to keep them happy, knowing they are the ones--along with the freshest of fish--who attract customers.

"We can't find a good chef in New York, or anywhere in the United States," Matsumota continued, defending his practice of bringing chefs in from Japan. Besides, he asked, what American--or Japanese, for that matter, would want sushi made by a non-Japanese.

It takes 10 years of training to become a first-rate sushi chef--surprising considering that little, if any, actual cooking is involved. He must know fish, how it look and feels at its freshest, and how to cut it artfully. A sushi chef must be able to peel a long white radish in a paper-thin roll so it can be shredded as an accompanyment to sashimi. And, most important, he must cook the rice to the proper texture for easy rolling and add just the right amount of vineger for flavor. Some regular sushi eaters swear they can tell which chef made the rice by its taste.

Kawasaki, a big smile on his face, wields his supersharp knife with the dexterity of a surgeon, slicing fish to order to fit the type of sushi or sashimi dish he is making.

Part of his talent is his showmanship, the ability to perform in full view of the public. In Japan, Kawasaki would be talking with customers as he works, something his limited English prevents him from doing with Americans. But he is learning the language, and his expressive face communicates without a need for words.

Matsumoto said it is not difficult to get super-fresh fish--the most important ingrediant for a sushi restaurant. Most of the supply is flown from New York daily, though specialties such as sea urchin, abolone and giant clam are shipped by air from the West Coast.

Occasionally Kawasaki will carry a choice morsel--such as the prized and rare fatty belly of tuna, called toro--under his arm on flights from New York. That's a happy day for the Japanese clientel of Takesushi, who prize Toro above all other fish, since it generally is unavailable here.

The simplest form of sushi is a bit of fish placed artfully atop a thumb-sized roll of vinegered rice that is seasoned with a bit of wasabi. Sometimes, though, rice placed on a thin slice of seaweed forms a bed for this fish. Then it is rolled with the help of a small bamboo mat, sliced and placed on a wooden tray so the colorful core of fish is showing. Often, fish roe or bits of sea urchin are placed on top of a small sphere of rice which is then wrapped in a slice of seaweed.

The Americanization of sushi has begun, though, with two new forms that are becoming popular here. One is the California roll, which is avocado and king crab leg wrapped in rice and seaweed. The other is a New York roll of chopped cooked salmon with a thin strip of cucumber wrapped in rice and seaweed.

Kawasaki fashions the New York roll with the light green cucumber strips, the pink salmon and white rice taking on a flower-like appearance as it nestles in the dark green seaweed cone.

A recipe for the California roll was even given in a recent food article by Craig Claiborne in The New York Times--assuring it a place in the archives of cooking.

Thus, while Japan sells its cars and electronics to the United states, Americans are developing new forms of sushi. That may contribute in some small way to a new balance of trade.