1250 24th St. NW. 202-466-2299. Open: for lunch Monday through Friday 11:30 a.m. to 2 p.m.; for dinner Monday through Friday 5:30 to 10 p.m., Saturday 5 to 9:30 p.m. Closed Sunday. All major credit cards. Reservations suggested. No separate non-smoking section. Prices: fixed-priced lunch $13.50 to $25, fixed-priced dinner $42 to $80; appetizers $4.50 to $22; entrees $5.50 to $33. Full dinner with drinks, tax and tip about $75 per person.

NO MATTER HOW MANY YEARS I eat, cook or study Japanese food -- and it's been 35 by now -- I still feel as if I've only scratched the surface. This is a cuisine as refined and subtle as classical music, and even more complicated to learn to appreciate.

So I don't hope to completely understand Unkai, the new and very expensive Japanese restaurant on 24th Street NW. The food is beautiful. It's exotic. But it is so esoteric I can't measure its authenticity by Japanese standards. I can only judge it as a Westerner.

My first impression of the main dining room was that it looked like an expensive copy of a Balkan communal dining hall. It is a large bare room with bare, knife-edge tables and a gray floor. At first it had no other color except on the plates. Later some artwork was added, and a screen in autumn shades fills the back wall. This is a severe room. As you look closer, however, the subtle beauty emerges -- the exquisite finish of those black wood tables that lets the grain show through, the wondrous translucent vases in shades of gray and white, the delicate imported rice paper that covers the walls. In the teppanyaki (grill) room, where diners sit around a marble counter inset with a grill where a chef performs, the decorative theme is the same, but the activity seems to enliven the very look of the room. There are also several small private tatami rooms, for traditional dining at low tables.

Since Japanese food is so esoteric, it is particularly important that the staff be able to communicate well with the diners. And while the gracious waitresses, who serve deftly and elegantly, now speak English much better than they did in the beginning, they are not able to elaborate on such menu descriptions as "appetizer" or "seasonal dish." Much of the menu, particularly the multi-course dinners, requires you to put yourself in the chef's hands and take what comes. But language lapses can lead to expensive mistakes. At one recent lunch, though I ordered the $16.50 sashimi and pointed to it on the menu, when the bill came I discovered I'd been served and charged for the $22 sashimi. And after I asked what the assorted appetizer was and decided against it, the waitress delivered a little plate of appetizers and explained it was the assortment. I assumed this was part of the lunch or a complimentary gesture for new customers. It turned out to be a $12 appetizer, so our final bill was $17.50 more than we expected.

That lunch for two cost more than $100 with tip -- and we drank only tea (be warned that a small glass of iced tea and each refill is $2.50). We left slightly hungry, having refused the waitress's offer of rice or soup because we were reluctant to escalate the bill further.

There are set lunches ranging from a tiny appetizer, soup and a meat or fish served on a lacquered tray ($13) to tempura ($17) or sushi ($18). The $25 bentoh lunch is a lacquered box containing perhaps two thin slices of delicious grilled fish, a tiny morsel of vegetable-stuffed fish roll, a mini plate of boiled vegetables, a flower-shaped mold of rice, a basket of tiny vegetable-and-egg cakes, a lone

shrimp and several beautiful wee morsels wrapped in leaves or seaweed, along with miso soup, four slices of sashimi and three pieces of pickle. Fixed-price kaiseki dinners start at $45. Basically, they are elaborations on the lunches, with occasional surprises such as a soul-filling chicken-studded porridge that tastes like a cross between polenta and matzo ball soup.

This is food for all five senses, but the set lunches are just a tease for the stomach. After lunch you will probably feel virtuous but would consider going out for another one. If you are brave enough to order a la carte, keep in mind that the best value on the menu is chicken yakimono ($5.50). This grilled chicken is a plateful of sliced room-temperature dark-meat chicken, faintly sweet and aromatic with sake and soy sauce, juicy and tender. Chawan mushi, a steamed custard spiked with sake and studded with bits of seafood and shiitakes, is a heartwarming discovery on a cold day. And grilled beef yakimono is a plentiful display of paper-thin raw beef to grill yourself over charcoal at the table, but it should be banned since it smokes up the place so badly that you sometimes have trouble seeing

across the room.

Every morsel of food gets respect here. Everything is cut with a jeweler's care, garnished with something charming -- a tiny maple leaf, a tangle of infinitesimal sprigs of herbs, a thin corkscrew of carrot, a sliver of bamboo knotted at one end -- and served on a plate that is so lovely you might have ordered it empty. Miniature baskets, petal-shaped bowls, flat slabs of china painted with flowers are the altars on which each cube of steamed egg or mound of grated radish with salmon roe is served. At dinner even the sake is brought with a tray of exquisite cups from which to choose.

Those are the niceties that seem to matter here. There is no great variety of food. In fact, the sushi assortment is mundane. But the fish is outstanding, particularly the raw salmon.

The tempura combinations -- including fan-cut shiitake mushrooms and julienned vegetables wrapped in a band of seaweed -- are slightly above routine. And if you order the tempura kaiseki dinner, you are served three courses of tempura: one of shrimp and vegetables, another of filleted fish and vegetables, the third of wonderful chopped seafood fritters. The quality of ingredients is unassailable and the batter is crisp and fragile. But the tempura is greasy. Still, the tiny stacked dishes of wasabi and daikon served to mix with the thinned soy dipping sauce reiterate that this is tempura above the norm.

Dessert is Unkai's Achilles' heel. Green tea ice cream is bland, and red bean ice cream is an acquired taste. The ginger ice cream is the only glory. And though sometimes the fruit has been an artistic arrangement of papaya, oranges and kiwi, one day we asked for grapefruit and were served a half sitting unceremoniously on a plate, ungarnished and clumsily cut.

The teppanyaki room is elaborate theater. The chef arranges and rearranges ingredients on the grill in precise geometry, and it is fascinating to watch him create a sauce on the flat grill, "stirring" and containing it with his spatula. Fixed-price teppanyaki lunches start at $13.50, but the dinners climb to nearly $50, and

a la carte ordering can easily add up to more. In ordering a la carte, I decided it was entertaining to watch the chef cook an order of vegetables, but not worth the $1 a bite. Sushi at $5.50 was a better addition to the lunch. But the a la carte lamb -- $15 -- would have been disappointing at any price. Two very fatty chops were cut up and cooked with the fat intact, then served barely pink rather than rare as requested. Seafood was more satisfactory. And a fixed-price lunch including shredded vegetables and tofu, bits of grilled vegetable, rice, miso soup and pickles along with the two scallops, two shrimps and salmon fillet turned out to be a festive event.

Much of the food at Unkai is strange, some of it is bland, most of it is delicious. And always it is beautiful. Unkai is an example of a tradition we can admire, but it is a restaurant designed for those who appreciate the nuances of that tradition -- and consider it worthwhile to pay the price for such exquisite subtleties.