Kutsukake Onsen is a secluded hot spring village nestled in the mountains of Tokanzan in Aoki Village, Chiisagata District, Nagano Prefecture. The hot spring dates back to the Heian period, when Provincial Governor Prince Shigeno healed his eye ailment by bathing in the waters and subsequently built a Yakushi-do hall to enshrine the guardian deity of the hot spring. Together with Tazawa Onsen, it has been designated as a National Health Resort Hot Spring, preserving the rustic atmosphere of a traditional therapeutic bathing village. The water is an alkaline simple hot spring with an exceptionally high pH of 9.5. The source temperature is approximately 39 degrees Celsius, making it a lukewarm bath ideal for long, leisurely soaking. Some baths are heated, allowing visitors to enjoy both lukewarm and warm water. The area is also known as Ogura-no-Yu because Mount Obogami resembles Mount Ogura in Kyoto. The waters are effective for hypertension, digestive ailments, skin diseases, neuralgia, muscle pain, rheumatism, diabetes, respiratory conditions, infertility, and menopausal symptoms. The quiet hot spring village consists of a few ryokan and the communal bathhouse Ogura-no-Yu, and is home to Manzanso, a member of the Japan Association of Secluded Hot Spring Inns.