Aji Nippon (moderate). You could almost miss this sliver of a sushi restaurant. Fans of the already snug Japanese eatery would love to keep it that way. Service is leisurely--only one waitress has been on duty when I've been there--but sushi is expertly done, as are cooked items on the menu. Besides sushi and sashimi standards like fatty tuna, yellowtail, salmon, and uni, there are intensely flavored novelties like cod roe and sea eel. Embellishments keep things interesting: rolls of crunchy aged soybeans, squid with plum, and fabulous fatty tuna with chili or scallions. Other high points on the menu are a briny seaweed salad, brittle and greaseless tempura, and delicate dumplings of seafood (shu mai) and meat (gyoza). Scallop teriyaki and beef tataki are winning dishes you'll wish were on more local menus.
Aji Nippon, 6937 Arlington Rd., 301-654-0213. Open Tuesday through Friday for lunch, daily for dinner.