Sushi bars come and go, but Mikado remains, and remains so very traditional. True, this old- fashioned Japanese restaurant has added a sushi bar this year. But the same motherly waitresses still serve, and the room is still as simple, pristine and soothing as we expect a restaurant in Japan to be.

Mikado serves reliably good Japanese food, the soups hot and full-flavored, the raw and cooked fish undeniably fresh, the tempura crisp and lacy. The sushi is fine, with a wide assortment that includes such modernities as Capitol roll (tuna, avocado and pickle, for goodness' sake!) and California rolls (the avocado with crab meat and without pickle this time). It is rather pricey, but you can order by the piece rather than by the pair. And there are plenty of teriyaki, rice, noodle and casserole dishes to keep nonsushi eaters happy while they accompany sushi fanatics.

The cold spinach could use more seasoning, the salad dressing is sharper and less balanced than it used to be, the teriyaki lacks a crustiness that would improve it. Still, for its lack of perfection, Mikado remains a pleasant restaurant with food you would probably welcome again and again for its simple, clear freshness. 4707 Wisconsin Ave. NW. 244- 1740. L $4.95-$15, D $7.25-$15. L daily ex Sun, D daily. Closed Mon. AE, CB, DC, MC, V. Res sugg. Full bar.