Kakinoki Onsen Hatonoyu is a day-trip hot spring facility nestled in the mountains of Yoshika Town, Kanoashi District, Shimane Prefecture, deep within the Chugoku Mountain Range. Known also as Kobo-no-Yu (Kobo''s Spring), the hot spring was discovered when a priest of a temple dedicated to Kobo Daishi struck a thermal water source. It has been cherished for centuries as a therapeutic bathing destination, attracting visitors from afar for its medicinal properties. The former village of Kakinoki, located at the southernmost tip of Shimane Prefecture bordering Yamaguchi Prefecture, is also renowned as a pioneer of organic farming in Japan. Originally operated as a public welfare facility called Hato-no-Yu-so, it was privatized and now operates as Kakinoki Onsen Hatonoyu.

The water is classified as a carbon dioxide-containing sodium-calcium chloride-bicarbonate spring (hypotonic neutral hypothermal spring), containing 1,020mg of free carbon dioxide, making it an authentic carbonated spring. With a pH of 6.3 and a source temperature of 29.1 degrees Celsius, it is technically a cold mineral spring with a remarkably high total mineral content of 3,182.7mg/kg. Rich in iron and carbonic acid, the water emerges transparent but gradually oxidizes upon contact with air, transforming into a distinctive bright orange turbid water reminiscent of persimmon fruit — the very fruit after which the village is named. The source water is delivered without dilution or recirculation in a free-flowing kakenagashi system, with steam injection used to heat the bathing pools.

The facility features rock-style main bathing pools and a jet bath using plain water, with separate indoor baths for men and women. The bathing pools are thickly coated with mineral deposits, a testament to the exceptional concentration of the spring water. The on-site restaurant Kaki-no-Sato serves cuisine prepared with locally grown organic vegetables and rice from the Kakinoki area. Day-trip bathing is available for 500 yen for adults and 200 yen for children, open from 11:00 to 20:00 (last admission 19:30), closed every Wednesday.