Kamanuma Onsen Daigi Izumi

The bath here has a hot pool and an unheated cold mineral spring sitting side by side, so you can alternate between them as long as you like. The bathing area is semi-open to the outside, right on a stream with forest on the far bank. Back in the lobby there's also a drinking spring to try. The inn is a member of Nihon Hitoyu wo Mamoru Kai (日本秘湯を守る会), a group dedicated to preserving remote hot springs in Japan. Meals lean toward local, herb-influenced cooking and are served in-house.