Bankei Onsen Yunotoya

Yunotoya is a small hot spring inn on the bank of the Osaru River in Bankei, Sobetsu Town, Usu District, Hokkaido. It stands about 300 meters along a town road after crossing the Bankei Bridge on National Route 453. Bankei Onsen itself dates back to 1882, and during the Showa era the hamlet bustled with coal miners and maintenance crews of the former JNR Iburi Line. Yunotoya opened in 1994, making it one of the newer inns in the area, and it is run by a single family with just ten guest rooms.

The water is classified as a simple hot spring, neutral, hypotonic and hot. The analysis certificate posted in the changing room, dated 10 July 2015, gives a source temperature of 70.2 degrees Celsius, pH 7.4, dissolved solids of 0.990 grams per kilogram and total components of 1.049 grams per kilogram. The water is colorless, transparent and almost without taste or smell. Supply is blended from four sources, and because the source water is very hot it is cooled with added fresh water before being run continuously through the tubs. There is no reheating, no recirculation and no chlorination, and free residual chlorine in the tubs has been measured as undetectable. Note that the inn's own website lists a separate analysis describing a sodium-calcium sulfate-chloride spring at 68.5 degrees Celsius.

The bathing area is separated by gender, with two indoor tubs, a medium-temperature bath and a hotter one rimmed in Kiso cypress, plus an open-air bath within earshot of the river. There is no mixed bathing, no private bath and no sauna. Day-trip bathing runs from 11:00 to 21:00, with last admission at 20:00, and costs 500 yen for adults and 350 yen for elementary school children. A rest room and the in-house restaurant Sansai are open to day visitors, and parking is free for about 30 vehicles. Overnight guests stay in nine Japanese-style rooms and one Western-style room, with check-in at 14:00 and check-out at 10:00.