Zaisu

A zaisu (Japanese: 座椅子) is a Japanese chair with a back and no legs. They are often found in traditional rooms with tatami mats, and are often used for relaxing under heated kotatsu tables. Zaisu come in many styles, and can either have a cushion built in or be used with a zabuton. For an even more relaxed seating arrangement, one may also use a Japanese style armrest called a kyōsoku (脇息).