Introduce yourself to the Japanese style of eating known as kaiseki (a meal of small tasting portions presented in a ritualized order) at this charming prix-fixe-only restaurant. First timers should order the omikase, or chef's tasting, to appreciate the true breadth of the genre. It may start with a wild mountain plum floating in a glassy cube of gelatin, and proceed to a gurgling pot of blowfish or to sweet lobster or delicate squid to be cooked on a hot stone. The experience is exhilarating. Subway: A, B, C, D, 1, 2, 3, 9 to 59th St.-Columbus Circle.