Matsukawa Onsen Kyounso is a secluded hot spring inn located at approximately 875 meters above sea level in Hachimantai City, Iwate Prefecture, surrounded by primeval beech and oak forests within Hachimantai National Park. As a member inn of the Japan Secret Hot Spring Preservation Association, it boasts over 250 years of history as a traditional therapeutic hot spring retreat. The source water is colorless and transparent, but transforms into a beautiful milky white color resembling a watercolor mixture of blue, green, and white when exposed to air. The spring quality is simple sulfur spring (hydrogen sulfide type) with a source temperature of 62.2°C, weakly acidic pH of 5.4, and a flow rate of approximately 240 liters per minute. It features 100% free-flowing source water and is beneficial for neuralgia, rheumatism, skin diseases, and diabetes. The inn's unique feature is its geothermal heating system utilizing 70°C sulfur spring heat, keeping guests warm even in winter. The large public bath was renovated in June 2024 with the introduction of cypress wooden buckets. The facility offers both mixed outdoor baths and women-only outdoor baths where guests can enjoy seasonal views of beech forests. Meals feature local iwana char, the rare Sakhalin taimen sashimi, wild mountain vegetables, and the specialty guinea fowl hot pot (Horohorodori-nabe).