Genshichi Roten no yu Zao Onsen

This rustic public onsen in Zao Onsen, Yamagata, is known for its generous open-air rotenburo pools set among forest and mountain scenery. The milky, sulfurous water comes from Zao's volcanic springs, long associated with skin-softening properties. An indoor tub is available when the weather turns, but soaking outside is the real draw, especially in winter when snow weighs down the surrounding trees and steam drifts into cold air above you. The onsen is a short walk from the central village, where a gondola ride up the mountain in winter brings you face to face with the famous juhyo, the frost-covered snow monsters that form on the trees.