Lit. "sand toilet." Originally a functioning toilet for use during tea gatherings, it later became a purely ornamental feature of the "inner tea garden" *uchiroji 内露地 when the functional toilet *shitabara setchin 下腹雪隠 was introduced in the outer roji. The evolution of the sunasetchin reflects the emphasis on cleanliness and purity found within the tea ceremony from the time of Sen no Rikyū 千利休 (1522-91).
Typically the sunasetchin is constructed with partially buried posts *hottate 掘立て and has a pent roof *katanagare 片流 or katayane 片屋根 often made with light boards of arrow-root vine. The entrance is on the gable side and a entrance stone tozuri-ishi 戸摺石 is placed at the door. Inside there should be two large foot-rest stones ashigake-ishi 足懸石 as well as the small stones: a urine stopping stone shōyōgaeshi-ishi 小用返石 or shōbengaeshi-ishi 小便返石 at the front, and the rear stopping stone uragaeshi-ishi 裏返石 at the back. There is also a dust hole *chiriana 塵穴 and a *sokujō 触杖 (sweeping board).
According to *Nanbōroku 南方録, Rikyū placed sand inside the setchin, and after the guests departed, took out the old sand and replaced it with fresh sand. Before guests come, water is poured over the area and then dry sand is piled up and the sokujō put into place.