Okushiobara Arayu Onsen Keiunkaku

Keiunkaku is the single inn of Okushiobara Arayu Onsen, set in a mountain hollow above 1,000 meters in Yumoto-Shiobara, Nasushiobara City, Tochigi Prefecture. Behind it rises Mount Io (Arayu-Fuji), which still emits volcanic steam; the white fumaroles and the scent of sulfur that hang over the area preserve the atmosphere of an old therapeutic spa village. The inn has upheld free-flowing sulfur spring water ever since Arayu Onsen was opened in the early Edo period, and it now counts three centuries of history. It is a member of the Japan Association of Secluded Hot Spring Inns.

The water is a simple acidic sulfur spring of the hydrogen sulfide type, acidic at pH 2.6. With total sulfur content of 55.8 mg per kilogram it ranks among the most concentrated sulfur springs in Japan, yet it is noted for a gentle, soft feel that does not irritate the skin. Although the source emerges at around 79 degrees Celsius, no water or heat is added, and every tub is filled with 100 percent free-flowing spring water. The milky white to grayish, cloudy water is traditionally valued for diabetes, high blood pressure, rheumatism and skin conditions.

The bathing facilities include an observation bath called Tanuki-no-yu, which looks out over the surrounding mountains, and a private garden open-air bath, Tanuki-myori-no-yu, overlooking a seasonal garden; overnight guests may use the private open-air bath free of charge. Day-trip bathing is offered from 12:00 to 14:30 for 1,000 yen per adult (towel included, observation bath only). From behind the inn, visitors can also tour the cloudy communal baths of Mujina-no-yu, Tera-no-yu and Naka-no-yu.