Kenji Oana and his fellow artisans work with practiced synchrony, alternating servings of nigiri and drinking snacks. Rice is seasoned with either red or white vinegar; sushi of tuna and pickled daikon radish is shaped like o-hagi (rice cakes coated with sweet red bean paste), a legacy inherited from his mentor along with the shop’s name. Snacks are delightfully inventive: baked and steeped barracuda and eggplant, for example, or conger eel grilled with Saikyo miso. Never knowing what to expect accentuates the fun.