Located near the Daibosatsu Pass trailhead in Enzan, Koshu City, Yamanashi Prefecture, Unposo is a hot spring ryokan and a member of the Japan Association of Secluded Hot Spring Inns. Founded in 1926 (Taisho 15), it temporarily closed during World War II in 1944 and reopened in 1979. The spring features an exceptionally high alkaline simple thermal water with a pH of 9.90 and a source temperature of 26.6 degrees Celsius (a cold mineral spring). The water is also suitable for drinking and has been cherished as a sacred spring by local residents since ancient times. The indoor bath is built directly into the granite bedrock, creating a rustic atmosphere, and one of the tubs allows guests to experience the 26-degree source water directly. The outdoor bath is divided into two pools: an upper pool (hotter) with a roof made from a single slab of Enzan granite, and a lower pool (cooler). Guests can bathe while listening to the sounds of the mountain stream. Nearby attractions include the Kurokawa Gold Mine, said to be Takeda Shingen's hidden gold mine, and the legendary Oiranbuchi site, making it popular among history enthusiasts. The inn serves cuisine made with rice and vegetables from their own garden, local beer brewed with hot spring source water, and over 30 types of local wine. The cozy inn has just 9 rooms.