One of Japan’s Secret Hot Springs, Hoshi Onsen is an isolated onsen deep in the mountains of Minakami. Hoshi Onsen’s sole ryokan, Chojukan has a few beautiful and rustic traditional baths, its most famous being a wooden, mixed gender, indoor bath where the water bubbles up straight through the stones on the floor of the tub.
Hoshi onsen is unique among all onsen in Japanese. Located near to where Gunma, Nagano, and Niigata prefectures come together, Hoshi was once a popular stop on the Mikunikaido, the trail that passes over nearby Mikuni Pass. Originally built in the 1870’s, the onsen is managed by the fifth generation of the Okamura family.
Part of its uniqueness comes from the fact that hot water flows directly up through a pebble and rock aqua filter — to say nothing of the baths materials — local cypress trees. Hoshi is said to one of only 50 onsen sites built directly at the source of the water, where no water is added to cool down or heat up the waters bathers soak in.