Furutobe Onsen

Furutobe Onsen is a single-inn secluded hot spring tucked deep along a forest road in the mountains of Ikarigaseki, Hirakawa City, Aomori, near the border with Akita Prefecture. Its origins trace to black-ore prospecting begun in 1958; hot water was struck during drilling around 1970, and the site opened as a bathing inn in the mid-1980s. With no mobile-phone or television reception, it is celebrated among Japanese onsen enthusiasts as the birthplace of todo-ne, lying on the flooded floor as water streams over the body.

The spring is a sodium-calcium chloride-bicarbonate-sulfate water, emerging at about 42.8 degrees Celsius with a near-neutral pH of roughly 6.2. Rich in iron, it shows a cloudy pale-brown tint and carries a metallic taste and scent. It is a fully free-flowing bath with no added water, heating, recirculation, or disinfection, earning the top Pure Onsen A certification.

The bathhouse offers only separate indoor baths for men and women, with two tubs. A copious flow said to reach 500 to 800 liters per minute streams across the floor like a river. Day-trip bathing is 400 yen for adults, open from 9:00 to 20:30.