The service ware at Kajitsu is worth studying. Most pieces are handmade, like the carved wood trays and the hammered metal chopstick rests and sake pitchers. Vintage ceramics with small chips show signs of repair, and their age underlines transience of the seasons that is a major theme of shojin ryori.

You could design a calendar simply by eating at Kajitsu every four weeks and taking pictures. Mr. Ueshima changes his menus on the first of the month, adding some plants that are at their peak and some that are on the rise. His dishes — four of them in a $55 tasting, eight in an $85 or $100 menu that ends with a bowl of matcha, green tea as thick and frothy as espresso — are drawn from the season, but they are also drawings of the season.

In June, he used a glossy dark magnolia leaf as the lid for a soup of slippery wakame seaweed and sesame tofu fried to a satisfying crunch. Last month, he lay pointy lily blades across a bowl that held a kind of vegan Jell-O salad, a clear gelatin dome studded with slices of raw baby okra, cooked bell peppers and mountain yam. To garnish that pea soup, the first dish on his April menu, he had made tiny replicas of pink-streaked cherry blossoms out of thin sheets of wheat gluten and rice flour, then decorated the bowl with a cherry branch whose flowers were so exquisitely small and delicate that they made other cherry blossoms look like the centerpiece at the wedding of a mobster’s daughter.

Anticipating the season and showing off local ingredients are both old kaiseki traditions, but I found that the things I enjoyed least at Kajitsu were Western vegetables that had not come into their own yet. Neither grape tomatoes with a vinegar jelly in April nor corn kernels in a golden fritter in June were as lush as they will be in July. And while Mr. Ueshima seems to reach for stronger, meatier flavors than Kajitsu’s first chef, Masato Nishihara, he doesn’t always have his predecessor’s delicacy.

The chef’s artistry, though, can make up for some of the flavor his ingredients might be missing on their own. His simmered tomato would still be very good in August; it is exceptional in June, a chilled poached plum tomato with slivers of juicy and spicy spring ginger set on shimmering tomato jelly that took its layers of depth from kelp and shiitakes.

Although the buckwheat flavor of the soba noodles made fresh each day could be a little more full-throated, they are as tender as they could be and still hold together. Rice, the last course before dessert, is a treat that can appear in many forms. Warm and fragrant, sharpened with vinegar, it made a bed for two rows of tender, cooked king oyster mushroom stems carved to look like slices of raw fish. Dab the mushrooms with nori paste and freshly grated wasabi, pinch some rice between chopsticks, and you have a deeply rewarding take on sushi.

Whether or not it is on your menu, you should drink matcha at the chef’s counter at least once. Mr. Ueshima will froth it with a bamboo whisk before giving the bowl three small turns. Then he sets it in front of you and gives a deep bow that brings you back to the roots of a meal that is more than a meal.