Tsukuba Onsen Hotel

Located partway up Mt. Tsukuba in Tsukuba City, Ibaraki Prefecture, Tsukuba Onsen Hotel is a single standalone inn. In 1974, after drilling deep into the mountain, the inn struck Mt. Tsukuba's first hot spring vein at a depth of 1,353 meters, and it has remained the mountain's only inn with its own private source ever since. Perched on high ground, its guest rooms and baths command sweeping views over the Kanto Plain.

The spring, drawn from the 'Tsukuba Onsen Waraku R1' source, is an alkaline simple hot spring with a temperature of 37–42°C. It is served as a genuine source-fed bath with no dilution, added heating, circulation filtering, or chemical disinfection, leaving the clear, colorless water with a smooth, slightly silky texture.

The bathing area centers on an open-air bath shaded by the trees of Mt. Tsukuba, a small tsubo-buro (jar-shaped bath) tucked within it, and an indoor bath scented with hinoki cypress, complemented by a private reservable bath, sauna, and hot stone bath (ganbanyoku). Day-trip bathing runs from 13:00 to 18:00 (last entry 17:00), priced at 1,100 yen for adults (1,300 yen on weekends and holidays), 700 yen for elementary school children, and 500 yen for infants. Guest rooms come in Japanese- and Western-style, with kaiseki-style fusion dinners blending Japanese, French, and Italian techniques.