Yuya Onsen Okudaya

Okudaya stands beside the Ohora River in Yuya, Osaka-cho, Gero City, Gifu Prefecture, on the western flank of Mount Ontake. Yuya Onsen is said to have been opened more than 450 years ago, and Gero City records describe a bathing resort with over four centuries of history, noted in Edo-period documents as a medicinal spring. Okudaya is the original source inn, preserving in its chronicle Onsen Yumoto Kaigen Yuraiki the tradition that a samurai named Magozaemon Okuda, suffering from stomach illness, discovered the spring. The inn itself was founded roughly 360 years ago.

The water is a carbon dioxide bearing sodium bicarbonate and chloride spring. It emerges at just 15.4 degrees Celsius, making it a cold mineral spring, with a total mineral content of 6,451 mg and an exceptional 1,947 mg of free carbon dioxide as its dominant component. Clear and tingling at the spout, the water turns yellow brown in the tub and deposits reddish mineral flakes. Because the source is cold it is warmed through a heat exchanger, but nothing is added to dilute it: the baths run on 100 percent spring water, with the inflow allowed to overflow. The inn holds an official permit for drinking the water, and a public drinking fountain sits at the entrance. The spring is recommended for chronic digestive complaints, diabetes, gout, liver conditions and chronic constipation, and is discouraged for kidney disease, hypertension, edema and diarrhea.

Bathing is limited to one indoor bath each for men and women, with no open-air tub. The men's bath has two pools, one filled with the untreated cold source and one built of river stones and warmed by heat exchange, allowing alternating hot and cold bathing. There are fifteen Japanese-style guest rooms sleeping up to fifty guests, and a shared kitchen supports long self-catering therapeutic stays. Meals feature Hida beef grilled on magnolia leaf with miso, char from local waters, and soba milled, kneaded and boiled the same day from buckwheat grown by the owners, with hot spring rice porridge at breakfast. Lodging starts at 13,350 yen per person with two meals, or 5,430 yen per night for self-catering stays of three nights or more. The inn is open year-round with irregular holidays, and no day-trip bathing is advertised.