Natsuse Onsen Miyakowasure

Miyakowasure is the sole inn at Natsuse Onsen, hidden in the mountains upstream of the celebrated Dakigaeri Gorge in Semboku City, Akita Prefecture. Local people had used the water as a healing spring since the Edo period, and the first inn opened here in 1904. The building was moved to its present site in the 1950s when the Jindai Dam was constructed, and the business closed in 2001. The company behind Myonoyu in the Nyuto Onsen area took it over and reopened it as Miyakowasure in August 2005. It stands alone inside the Dakigaeri Gorge Prefectural Natural Park, with no other houses nearby.

The water is a sodium and calcium sulphate spring, hypotonic and mildly alkaline. A re-drilling of the source in September 2018 left the mineral character unchanged but sharply increased both the flow and the temperature, which now emerges at roughly 59 degrees Celsius. The posted analysis gives a pH of 8.4 and a modest dissolved mineral content of about 890 mg per kilogram. The water is clear and colourless with the faintest trace of hydrogen sulphide. The inn declares no added water, no heating, no recirculation and no disinfection, so every tub on the property, from the private balcony baths to the main bathhouse, runs on free-flowing spring water.

All ten guest rooms have their own open-air bath fed directly by the source. In addition there is a separate indoor bathhouse for men and women, open around the clock and divided into a cooler and a hotter tub, plus a reservable open-air bath that overnight guests may use free for thirty minutes. Day bathing and lunch service have been suspended until further notice under an official announcement dated 11 April 2026, so the baths are currently reserved for staying guests. Two-meal stays are currently listed on major booking sites from around 80,000 yen for two people.