Actually, this onsen is attached to Azumiya Ryoukan, which is regarded as a hidden springs location in Yamagata. The reason for posting this photo was because it showcases a single bath made from a tree trunk. Again a harmony between water, earth, and wood.
And then the views! Autumn and winter would be perfect times of the year to be up here. Of course getting here is best by car, the only way actually. Crisp chill air and nice aromatics from the steam is excellent.