[Access] About 20 minutes by car from Nihonmatsu IC on Tohoku Expressway
[Webpage] Adatara Resort Okudake no yu (Japanese)

During my hike up Mt. Adatara, I had been looking forward to soaking in the hot spring at Kurogane-goya Hut, but unfortunately it was closed for construction. I was planning to head down to Dake Onsen at the foot of the mountain instead, when I noticed that Okudake no Yu is attached to the ski resort that also serves as the trailhead. Overcome by the urge to wash off the sweat right there, I decided to give it a try.

Okudake no Yu is a clean and well-maintained facility with both indoor and open-air baths. Around Kurogane-goya along the Adatara hiking trail, the smell of sulfur is quite strong, so I expected this to be another sulfur-scented spring. Surprisingly, however, the water here is almost odorless. The pale bluish-white water still has a sharp sourness and a slightly bitter taste when sampled, so it clearly contains sulfur components—but the lack of smell makes it feel oddly mysterious.

The water at Okudake no Yu is a blend of five different sources, with a total mineral content of 745.7 mg/kg and a pH of 2.5, classified as a simple acidic hot spring. More than anything, what makes this onsen special is its incredibly open and spacious outdoor bath. As you can see in the photos on the Adatara Resort – Okudake no Yu website, there is nothing blocking the view, allowing you to enjoy the hot spring while taking in the magnificent scenery right in front of you.