Metou Onsen is the oldest hot spring in the Tokachi region, opened in 1901 (Meiji 34) and established as a business in 1904 (Meiji 37), with over 120 years of history. The name derives from the Ainu word 'metot,' meaning 'deep in the mountains,' and true to its name, it is a solitary inn surrounded by pristine primeval forest along the Nukanan River flowing from the Daisetsuzan Mountain Range.

The hot spring is an alkaline simple spring (pH 9.5) with a source temperature of 60°C and a natural flow rate of 230 liters per minute, offering 100% source-fed hot spring water without any heating. Temperature is adjusted between high-temperature baths (about 44°C) and standard-temperature baths. The water feels silky smooth on the skin and is acclaimed as 'Hokkaido's finest quality hot spring.'

Bathing facilities include the riverside 'Kyogan-no-Yu' (Giant Rock Bath) open-air bath, the 'Large Open-Air Bath' accommodating up to 20 people, the riverside 'Small Open-Air Bath,' and indoor baths with different atmospheres facing the river and mountain sides. The Giant Rock Bath operates with different schedules for men-only, women-only, and mixed bathing (bathing attire required for mixed bathing, rental 300 yen). At night, guests can observe Ezo deer coming to drink from the illuminated riverside hot spring from the bath, and may also encounter Hokkaido foxes and Blakiston's fish owls.

Visitors can enjoy spectacular seasonal scenery including spring greenery, autumn foliage, and frost-covered trees created by hot spring steam in winter when temperatures drop below -20°C. Located about 40 minutes from Ashoro town center with 3km of unpaved road access, this secluded hot spring is certified by the 'Japan Secret Hot Springs Protection Association.' The two-story wooden inn has 7 rooms (including 1 with private open-air bath and 1 with bath and toilet) and operates year-round.