Akakura Onsen Yumori-no-Yado Sannojo

Sannojo is a hot-spring inn on the banks of the clear Oguni River in Mogami Town, Yamagata Prefecture. Akakura Onsen is an ancient spring said to have been discovered in 863 by the Buddhist monk Jikaku Daishi Ennin, and Sannojo itself was founded in 1891. Its celebrated Oiwaburo (great rock bath) was carved out of an enormous natural boulder by hand some 300 years ago by the first-generation owner, Takahashi Sannojo, and the inn is a member of the Association to Protect Japan's Secret Hot Springs.

The water is a calcium-sodium sulfate spring with a mildly alkaline pH of 8.2 and a source temperature of 62.3 degrees Celsius. The inn draws on two of its own sources, and every bath is free-flowing (kakenagashi). The great rock bath is a rare ashimoto-yusshutsu bath, where the hot spring wells up directly through cracks in the stone floor of the tub. The clear, colorless water is said to relieve nerve and muscle pain, poor circulation and fatigue.

The bathing facilities comprise the great rock bath with deep, high and middle pools, a roofed open-air bath overlooking the Oguni River, and a private 40-minute gourd-shaped bath, all separated by gender. Overnight stays start at 8,250 yen with two meals, and day-trip bathing costs 500 yen for adults and 300 yen for children, available from 10:00 to 16:00. Free parking for 30 cars is available, along with a free shuttle from JR Akakura-Onsen Station.