Mantenboshi no Yu.

The design strongly reminded me of Station of Flower Katashina Hanasaku Hot Spring: similarly beautiful rotenburo with mountain views. Inside, besides the main bath, there's a sauna, a cold bath, and a nuryu (just lukewarm, pleasant — today they even put a bag of apples in it for good vibes). Outside there are several baths, one of them is a jacuzzi, and it's done really well. No photos at all since it was quite crowded, being Saturday. The water is mildly alkaline, pleasant, but with no color or smell. They say kashikiri (private baths) are available. Entry is 800 yen for 3 hours — at the entrance they give you a sign with the time, then you return the sign and get the shoe locker key. Tattoos not allowed. Inside there's a shop and various other entertainment and spa treatments.