Nyuto Onsen Kuroyu

Hidden in the forested mountains of Akita in northern Japan, Kuroyu Onsen belongs to the small circle of seven ryokan that make up Nyuto Onsen village. Its history goes back to 1674, when the spring is said to have served as a traditional bath for the Satake Hokke family, who ruled the castle town of Kakunodate — nearly 350 years of continuous use, a rare anchor in the story of Japan's Edo-period baths.

Its name, meaning "black hot water," refers to a sulfurous spring rich in hydrogen sulfide, the largest in volume of any bath in Nyuto Onsenkyo. The inn keeps a rustic, secluded atmosphere of wooden buildings and outdoor pools set in forest, closing each winter from November to mid-April — a timeless retreat far from any road.