Amakazari Onsen Amakazari Sanso

A single secluded inn at about 960 meters elevation at the northern trailhead of Mount Amakazari, one of Japan's 100 famous mountains, in the Kajiyama district of Itoigawa, Niigata. A record from 1818 (Bunsei 1) notes a petition to develop the spring, and from 1880 (Meiji 13) the site served as a mountain lodge and climbing base for Mount Amakazari. It is a member of the Japan Secret Hot Spring Preservation Society. Until a road reached the inn in 1999, it could be reached only on foot, deep in the folds of the mountains.

The spring is a sodium bicarbonate-chloride spring (hypotonic, neutral, high-temperature). The source emerges at about 47.4 degrees Celsius with a pH of 6.6, rich in carbonate, carrying a faint salty taste and a refreshing quality. It is served as pure free-flowing water with no added water or heating, and mineral deposits form around the spout.

Alongside separate indoor baths for men and women, the garden holds a mixed-gender open-air bath called Miyako-wasure-no-yu. Day-use bathing is 500 yen for adults and 250 yen for children during the operating season (hours by inquiry). Overnight stays are in a simple 12-room lodge, from around 9,000 yen per person with two meals; because the inn runs on its own generator, lights go out at 9 p.m. The inn is open from early May to early November and closed in winter.