Futamata Onsen Kashiwaya Ryokan

Kashiwaya Ryokan is a riverside inn in Futamata Onsen, in the mountains of Tenei Village, Iwase District, Fukushima Prefecture. It has been run by the same family for four generations. Its signature Jifuki Iwa-buro is a basin chiseled out of the bedrock, with hot water welling up through the floor; the bath is said to date back to the Meiji era.

The water is a calcium sulfate spring (formerly called a gypsum spring) with an alkaline pH of about 8.7 and source temperatures of 45.8 to 52.5 degrees Celsius. The inn draws on five sources: the rock bath and the Taki-no-Yu each have their own, while the cypress bath and its open-air bath share a blend of three. Every bath is fed by free-flowing source water with no recirculation and no heating, although water may be added to cool it in hot weather.

The baths are the Taki-no-Yu and the cypress bath, each with an open-air bath and alternating between men and women, plus the rock bath, which is reserved for private use. Day-trip bathing is 880 yen for adults and 550 yen for children from 11:00 to 14:00, with irregular closing days, so a phone call beforehand is advised. The inn has 10 rooms, with rates from 14,300 yen per person with two meals.