Nishiyama Onsen Yushima-no-Yu

Yushima-no-Yu is a town-run hot spring facility set along the Hayakawa gorge in Hayakawa Town, Yamanashi Prefecture, deep in the foothills of the Southern Japanese Alps. The surrounding Nishiyama Onsen district is said to have been opened in 705 AD and has supplied hot water continuously for more than 1,300 years as a remote mountain healing retreat. The facility was developed by Hayakawa, the least populated town in Japan, and is operated today by the Hayakawa Town development foundation.

The water is classified as a sodium sulfate and chloride spring, hypotonic and alkaline. It emerges at roughly 47 degrees Celsius with a pH of 9.8, a total mineral content of 1.1707 g/kg, and a flow rate of about 100 liters per minute. The water is clear and colorless with a faint sulfur note, and bathers describe a distinctly silky feel on the skin. No water is added, no heating is applied, and there is no recirculation or chlorination, making this a genuine 100 percent free-flowing source. A designated drinking spout is also provided.

Unusually, the bathhouse consists only of open-air baths with no indoor tub. Rock, wood and stone baths rotate between men and women. Day bathing costs 700 yen for adults and 300 yen for elementary school children, with hours from 10:00 to 18:00 (until 19:00 in July and August). The facility closes on Thursdays, with additional closures on the second and fourth Fridays from December through March. A tatami rest hall, a small shop and five self-catering cottages support longer therapeutic stays.