Gandatekyo Himeshaga-no-yu

Himeshaga-no-yu is a day-use hot spring bathhouse at Ochiai in Osaka-cho, Gero City, Gifu Prefecture, standing at the mouth of Gandate Gorge beneath Gandate itself, a 72-meter wall of columnar lava left by an eruption of Mt. Ontake. It belongs to the Hida-Osaka hot spring district, and the carbonated water that rises here is said to have been known locally for more than three hundred years. The name comes from himeshaga, a wild iris that grows in the surrounding hills. High fuel costs forced a long closure from January 2023, but the bathhouse reopened on weekends from 1 June 2024, and since 20 March 2026 it has operated on Fridays, Saturdays, Sundays and public holidays.

The spring is a carbon-dioxide-bearing sodium-calcium bicarbonate and chloride cold mineral spring. The analysis dated 10 May 2022 records a source temperature of 22.3 degrees Celsius and a near-neutral pH of 6.62, with 7.669 grams of dissolved solids per kilogram and a remarkable 1,171.2 milligrams per kilogram of free carbon dioxide, placing it among the most strongly carbonated waters in Japan. Because the source erupts intermittently under gas pressure, its yield cannot be measured. The water is a cloudy yellow-brown carrying brown mineral flakes, with a faint fizzy taste, a trace of salt and a scent of iron and rust. The drinking fountain outside the entrance is licensed by the public health authority, and visitors may fill their own bottles.

Bathing is separated by gender. The open-air Gensen Sonomanma-buro, literally the source-as-it-is bath, is served with unheated water at roughly 22 degrees Celsius, while the large indoor tub is warmed to about 36 degrees, the temperature at which carbon dioxide dissolves most readily, so bathers can compare the same spring at two temperatures. Both are free-flowing. The facility also has a Finnish sauna, a cold plunge fed by the unheated spring, and a bubble bath filled with well water. Admission is 950 yen for adults from junior high school age, 500 yen for elementary school children and free for younger children. Bathing runs from 10:30 to 21:00 with last entry at 20:30, and the restaurant Himetei serves dishes cooked with the mineral water alongside Hida country cooking. There is no accommodation on site.