Open Tuesday through Friday, noon to 2 p.m. and 6 to 10:30 p.m.; Saturday, 3 to 10:30 p.m.; Sunday, 3 to 9 p.m. No credit cards. No reservations on weekends.

Food: Pristine raw fish and a slight menu of cooked Japanese dishes.

Style: Tiny, delicate, deceptively simple

Price: Main dishes about $5, full sushi dinners $8.75.

BEHIHANA advertisements notwithstanding, one of the greatest advances in dining out in Washington over the last few years has been the sushi bar. Raw fish is not for everybody, which is perhaps why the newest sushi bar, Samurai Sushiko, has only a half dozen tables and thirteen bar stools. Sushi lovers don't often bother to make converts, being happy to let the squeamish stick to tabletop grilled steak bits and leave more raw fish for the addicts. But sushi and sashimi, Japanese raw fish on rice cakes or served alone, are highly developed example of the art of simplicity, of such beauty that it can be appreciated even in the abstract.

Not all the enjoyment of sushi, in other words, is in the eating. There is the watching - the hypnotic sight of nimble hands slicing raw fish into thin slabs, scooping a small oval of cold rice from a bowl, flipping on a bit of green horseradish paste, positioning the fish on the rice, arranging the sushi on a plate with an eye to color and space, adding a garnish of parsley or a carrot carved into a flower. Lest it become too repetitious, the process is varied by rolling a large rectangle of rice on a blue-black seaweed sheets to make a pinwheel centered with a bit of green (spinach), tan (shavings of pickled squash), black (dried mushrooms), yellow (steamed eggs), or to form a seaweed boat filled with rice and topped with coral salmon eggs and green-and-white cucumber, or with pale sea urchins. Sometimes the hands will slice cucumbers into grass like fringe, cutting through at regular intervals, all done at a rapid pace without the chef even looking at his hands.

The chef. He wears a colorful cotton sweatband tied across his forehand. He remembers customers from his previous sushi bar at Sakura, though he might not have seen them in a year or two. He chooses filets of fish from a glass-walled array along the front of the sushi bar and turns them into intricate mosaics outlined in seaweed, or simple plates of sashimi garnished with shaved pickled ginger and accompanied by a tiny pool of sauce for dipping.

The waitresses. Kimono-dressed. Smiling and bowing slightly, and bringing extra plates, mugs of tea, napkins, anything that might make your visit more comfortable.

The setting. Soft Japanese music. Satisfying Japanese block prints on the cushions of the booths and bar stools. Tiny curtains and tablecloths repeating the deep blue color theme, hanging paper lamps providing soft lighting. Hand-blocked cloth prints enclose menus, the text in calligraphy on handmade paper.

The tables. Blue or white cloths, chopsticks, earthenware and lacquer bowls, the plates pottery slabs small and appealingly rustic.

The drink. Tea, of course, in large mugs without handles. pale green-gold and highly scented. Japanese beers. Warm sake in miniature pitchers, to sip from doll-sized cups. Or sweet, springlike plum wine.

The hot food. So ups in Japan are thin and pretty, the clear suimono floating bits of mushroom and bean curd cubes, the opaque misoshuru less decorated. Both are drunk from a lacquered bowl, both are light and salty, more a warm beverage than a western sort of full-bodied soup. Yosenabe is the most serious competitor to the sushi at Samurai Sushi, it being a family-size bowl of sea-scented broth densely populated with fish, king crab, clams, shrimps in the shell, bean curd and lightly cooked greens. Fish is, indeed, thing at Samurai Sushiko. The yakitori - three small skewers of soy-sauced grilled chicken - is tasty, but quite a delicate portion for $2.50. Tempura, at $5, consists of five long, thin, lacy-crusted shrimp with four pieces of similarly battered vegetables, again a lightweight portion and not as successful as the sushi or yosenabe. The rest of the menu is not but an occasioanl appetizer of the day, and a few plains desserts - fruit from cans or cookies from bags. Sushi is the reason for visiting this restaurant, sushi in about two dozen varieties plus any that the sushi aficionado can think of to order ahead. Sushi of dark rosy tuna, of cooked pink shrimp, of purple-edged octopus, of translucent flounder, of eels and porgies and abalone and yellowtail and herring and eggs and kelp and giant sliced scallops. What can be found fresh is here very fresh - the fish filets are firm and sweet - but what must be obtained frozen - those enormous scallops, for instance - carries not quite the same pristine texture and nuance of flavor. Still, a meal of Samurai's sushi is an occasion of purity and subtlety, of contrasting sharpness and intensity, almost a ceremony.

The bill. Sushi is not cheap, but fish, especially the highest quality, freshest of fish, has long been priced out of the budget-food category. An assortment of sushi - eight pieces - costs $5.50, but one should not expect to stop there. Or maybe even start there. Most of the sushi costs $1.50 to $2 for two pieces, and one should start by sharing a couple of varieties, continuing from there. Yosenabe is $5, soup seventy-five cents, beer and wine from $1.25 to $2.50. Bring a $10 bill and feast on greater variety.