Yatsugatake Jomon Natural Hotspring Togariishi no Yu

The outdoor bath sits in a grove of tall trees and takes the form of a comma-shaped rock pool, designed by Goto Tetsuya (後藤哲也), known for his work at Kurokawa Onsen, to evoke a Jomon-era wild spring. Water runs fresh without recirculation (kakenagashi, 源泉かけ流し), turns a cloudy greenish-brown as minerals settle, and leaves skin notably smooth after soaking. Because there is no drainage system in the outdoor area, soap and shampoo are not permitted there; straw sandals are provided since algae grow on the pool floor. A private indoor tub (kashikiri, 貸切) is available in 50-minute sessions, with a washing area. There is also a separate drinking spring on site. The facility has operated as a day-use-only bath since around 2017.