Nuruyu Onsen Sato Ryokan

Sato Ryokan stands alone in a river gorge along the upper Hasama River on the southern flank of Mount Kurikoma, in the Hanayama district of Kurihara, Miyagi Prefecture. The spring is said to have emerged around 1150, in the late Heian period, when a landslide opened the ground. During the Edo period the Sendai domain placed its Nuruyu border checkpoint here to watch the frontier with the Akita domain, and the remains of that guardhouse are now a National Historic Site. The spring was long called Nuruyu, meaning lukewarm water, until volcanic activity on Mount Kurikoma in the Meiji era raised its temperature and the name was rewritten to mean warm water.

The water is a sodium chloride spring, hypotonic, weakly alkaline and hot, emerging at 64.4C with a pH of 7.5. It is served at 100 percent free-flowing source water with no added water, no reheating, no recirculation and no chlorination, settling to around 40 to 43C in the tubs. The water is clear and virtually tasteless, with a faint sulphur note at the spout and a slight slipperiness on the skin.

The source dried up after the 2008 Iwate-Miyagi Nairiku Earthquake and the inn was closed for roughly twelve years, reopening for day bathing in November 2020 and for overnight stays in 2021. Bathing is in gender-separated indoor baths only, the men's bath divided into two sections with stacked stone walls that evoke a rock pool. Day bathing costs 500 yen for adults and 300 yen for elementary school children, from 10:00 to 19:30, closed Tuesdays and Wednesdays. Eleven Japanese-style rooms are available from 5,100 yen room-only and 8,950 yen with two meals.