An air of downtown exclusivity has seeped into the Upper East Side, where a seat at this diminutive sushi joint is harder to snag than one at the latest It restaurant. Score a place in one of the three omakase-only seatings and you'll be dining on nigiri turned out by a Morimoto alum. They're not as dainty and refined as the ones at other premium fish houses, but Toshio Oguma isn't serving run-of-the-mill California rolls, either. The chef dispatches stripped-down offerings at a price that won't make you wince. Smoked bonito is brightened by a fleck of ginger, tangerine-colored salmon singed lightly for a bit of chew, and the sweetness of juicy botan ebi offset by a teacup of briny shrimp broth. The quality will please purists, even if the Adele and J-pop soundtrack won't; still, New Yorkers looking for an intimate alternative to hush-hush sushi dens should sit in on bandanna-clad Oguma's nightly dinner parties.