Shiroi Onsen no Yado Shirogane

The onsen water is milky white and faintly sulfurous, piped straight from the source and run through the tub rather than recycled, so it stays fresh. There's a small indoor bath and a rotenburo outside that the inn itself calls a forest bath, shinrin-yoku (森林浴): the water there runs cooler than indoors, and you can hear birds and leaves while you soak. Shirogane is tiny, just a handful of rooms, set a little apart from the center of Norikura Kogen. They take few guests at a time, so the bath is often yours alone. The name, "the white onsen inn," is a fair description of what's in the tub.