Hirao Onsen Miharashinoyu

This day-use bathhouse sits on high ground above Saku, with an indoor bath area (plain hot water, a carbonated bath, an alternating-temperature tub, a cold plunge, and a sauna) and an outdoor side with a rock-lined bath, a natural onsen tub, and a small pot bath, tsuboyu (壺湯), that runs noticeably cooler than the rest. The water has a soft, faintly smooth feel on the skin. It sits next to a ski resort and a highway parking area, so it fills with skiers and long-distance drivers alike, and the outdoor baths look out over Tateshina and the Yatsugatake range, a view that holds up after dark as well as by day. There's a restaurant on site and a separate heat-therapy zone, ganbanyoku (岩盤浴), though that's adults-only and can't be used without also bathing.