Rikyuan is an old soba restaurant in Nihonbashi, Tokyo, serving buckwheat noodles. Its signature dish is natto soba, thin white noodles topped with natto, egg yolk, kaiware, and seaweed, and tempura and sobayu are also served. Soba is ordered on the first floor and in the basement, while set meals are ordered on the second floor. On a weekday at 11:50 a.m. there was no wait to get in, and prices run high for the amount of noodles.