Kamiyuso is a secluded single-inn hot spring ryokan nestled along the Kamiyu River in Dedani, Totsukawa Village, Yoshino District, Nara Prefecture. Kamiyu Onsen was discovered during the Kyoho era (1716-1736) when local villagers found hot water bubbling up from the earth. The inn is also known as the place where celebrated author Ryotaro Shiba stayed for an extended period while researching for his masterwork Streets to Travel. In 1985, the area was designated as a National Health Resort Hot Spring together with Yusenchi and Totsukawa onsen under the collective name Totsukawa Onsen-gou.

The spring water is a sodium bicarbonate spring (low osmotic pressure, mildly alkaline, high temperature) with a source temperature of 76.6 degrees Celsius, pH 8.3, and a flow rate of 124 liters per minute. The water flows directly from the source without chlorine disinfection (20 percent dilution with fresh water during July to September). Rich in yunohana mineral deposits that float visibly in the water, this bicarbonate spring is celebrated as a beauty spring that leaves the skin remarkably smooth and moisturized, and is reputed to be beneficial for atopic dermatitis.

The inn features eight bathing facilities in total: two indoor baths and six outdoor baths. The riverside open-air baths Ranpu-no-Yu and Mizu-no-Kami offer views of the Kamiyu River gorge and the primeval forests of the Kii Mountains. Private outdoor baths such as Iyashi-no-Yu and Bihada-no-Yu provide intimate bathing experiences with distinct atmospheres. Kamiyuso is a member of the Japan Association of Secluded Hot Spring Inns and is widely regarded as one of the finest hidden hot springs in the country.