Mokubutani Onsen Kibedani Onsen Matsunoyu

Kibedani Onsen Matsunoyu is a secluded day-trip hot spring facility nestled in the mountains of the Chugoku Range in Kibedani, Kakinokimura, Yoshika Town, Kanoashi District, Shimane Prefecture. The origins of this hot spring date back to when villagers built a small hut near a natural spring on the mountainside, drawing the water into iron tubs and heating it with firewood. The current Matsunoyu facility opened in 1988. Its most remarkable feature is its geyser-fed source — one of the rarest in Japan — where underground carbon dioxide gas pressure causes the hot spring water to erupt spectacularly to a height of approximately 2 meters at intervals of about 25 minutes, continuing for around 5 minutes each time. After a three-year closure, the facility has resumed operations on an irregular schedule, primarily on weekends.

The water is classified as a carbon dioxide-containing sodium-calcium chloride-bicarbonate spring with a mildly acidic pH of 6.3. The source temperature is approximately 20.5 to 20.7 degrees Celsius, classifying it as a cold mineral spring. A unique heating system uses steam from a boiler to warm the water, and bathers can personally adjust the temperature by operating a valve to control the amount of steam. Due to its high iron content, the water is colorless and transparent when it first emerges but oxidizes upon contact with air, transforming into a murky tea-brown color with a transparency of only about 3 centimeters, indicating an exceptionally mineral-rich composition. The bath operates as a genuine free-flowing source spring.

The facility features indoor baths only, with separate bathing areas for men and women. The building exudes a charming Showa-era retro atmosphere. A rest area with kotatsu heated tables and a small dining area serving udon noodles are also available. Admission is 600 yen for adults, 300 yen for children under 13, and free for children under 3. Operating hours are 10:00 to 16:00, but as the facility currently operates on an irregular schedule, visitors must check the official Instagram account before visiting. Free parking is available for 50 vehicles.