“We do not serve American-style rolls.” Just beyond the entrance, that’s what the sign says at Ikko, a library-quiet retreat that prides itself on sushi and a sort of freestyle Japanese cuisine.

Despite the sense of hush, cave-like vibe, small size of its counter and smattering of tables, there is a surprising conviviality among the diners here as they nibble on an array of delicious options—ranging from multiple omakase menus to traditional à la carte. A board lists the dozen or so fish that have arrived as specials that day. Every item is sure to make the most of such immensely fresh seafood. Highlights include a slice of fatty otoro; red snapper topped with a tangle of sweet onions; chicken grunt hit with wasabi; and a perfect bite of firm hamachi.