Ubayu Onsen Masugataya

Ubayu Onsen Masugataya (姥湯温泉 桝形屋) sits at the end of a narrow mountain road in Yamagata, surrounded by jagged reddish-brown rock faces that drop straight into the gorge. The spring runs free-flowing without added water or heat, and the water comes out milky white with a clear sulfur scent. There are two open-air baths: a mixed rotenburo (露天風呂) with the cliff wall right in front of you, and a separate women-only outdoor bath. Indoor baths for men and women are available around the clock for guests. The ryokan has been in operation since 1533, now in its 17th generation, and belongs to Nihon Hitoyu wo Mamoru Kai (日本秘湯を守る会), the association of remote traditional hot springs. According to local tradition, the founding ancestor discovered the spring when he stumbled upon a mountain crone bathing there and she told him to become its keeper. The inn closes for winter from early November through late April.