Shiobara Motoyu Onsen Hitou-no-Yado Gensenkan

Gensenkan is a single-inn hot spring in Yumoto-Shiobara, Nasushiobara City, Tochigi Prefecture, standing at the far inner reaches of the Shiobara hot spring region known as Motoyu Onsen. The spring is said to have been discovered some 1,200 years ago by the monk Tokuitsu Daishi, and Motoyu once flourished as the heart of the Shiobara district before it was destroyed by a landslide following a great Edo-period earthquake and later revived. Gensenkan reestablished itself as a yumori (spring keeper) inn in 1884, and for more than 140 years it has safeguarded this remote hot spring deep in Oku-Shiobara.

The water is a sulfur-bearing sodium chloride-bicarbonate spring of the hydrogen-sulfide type, drawn from three of the inn's own sources: Takao-no-yu, Kantan-no-yu, and the Gensenkan new bore. Its total sulfur content of about 72 mg is among the highest in Japan, and the cloudy water shifts between milky white, greenish white, and occasionally ink-black depending on weather and season. The source emerges at around 50 degrees Celsius with a pH of 6.4 to 6.8, making it a remarkably soft, near-neutral bath despite its dense, opaque appearance. It is a fully free-flowing spring, and the Kantan-no-yu features a drinking station, its water said to benefit the stomach.

The baths include several tubs along the mountain stream, among them Takao-no-yu with open-air and indoor baths, the mixed-bathing rock bath Kantan-no-yu, and a cypress bath. Day-trip bathing costs 800 yen for adults (a two-hour window between 8:00 and 20:00, or 400 yen with a bath-hopping pass). Overnight stays are also available, letting guests savor this secluded spring in a quiet setting overlooking the stream.