Zaō Onsen

Nineteen centuries on the west flank of Mount Zaō

Zaō traces its founding to the year 110 CE. The legend belongs to the eastern campaign of the semi-mythical prince Yamato Takeru: one of his retainers, a warrior named Kibitsuhiko no Mikoto (also read Kibi no Takayu), was struck by a poisoned arrow and stumbled on a hot spring deep in the volcanic forest. He bathed, recovered, and gave the place his name. For most of its history the village was known as Takayu, "high springs," and it served as a quiet toji bath for pilgrims walking the Zaō ridge.

The modern resort is a twentieth-century creation. Roads reached the springs in the Taishō era, and in 1925 the area opened one of the earliest ski grounds in northern Japan. Inns expanded into hotels and pensions through the post-war decades, and the village was eventually absorbed into the city of Yamagata. Today it sits at about 880 meters on the western slope of the Zaō volcanic range, the spa town and the ski mountain functioning as one organism.

Acid sulfur and the ravine bath

The water is what people come back for. Five source groups feed roughly 47 individual springs, pouring out about 5,700 liters per minute of a strongly acidic sulfur-aluminum-sulfate-chloride water at pH 1.25-1.6, among the most acidic onsen waters in the country. The smell of sulfur hangs over the village, the milky discharge runs through every street channel, and the local nickname bijin no yu (beauty spring) has stuck for centuries because the acid water sloughs old skin in a way few other onsen can match.

The signature bath is the Dai-rotenburo, a series of open-air pools terraced down a wooded ravine on the edge of town. It runs from spring through late autumn and closes when the snow arrives. Steam rises through the cryptomeria, the water reaches the upper pool at scalding temperature, and the rocks below are stained chalk-white by decades of mineral deposit.

Skis above, crater lake beyond

In winter the village turns into the lower station of Zaō Onsen Ski Resort, one of the largest in Tōhoku and the place most associated with juhyō, the snow monsters: Maries' fir trees on the upper mountain encrusted by rime ice into hulking white forms, lit at night from late December through February. In the green season the same ropeways carry hikers up toward Okama, the cobalt-green crater lake at the summit of the Zaō range, perhaps the most photographed volcanic feature in northern Honshū.