Tsubame Onsen Shomyo-daki no Yu is a wild hot spring (noyu) located on the hiking trail from Tsubame Onsen in Myoko City, Niigata Prefecture. This open-air bath is set at the basin of Shomyo Falls (also known as Komyo Falls), located at approximately 1,400 meters elevation, about 40-50 minutes uphill from Tsubame Onsen parking lot. It's a popular spot among hikers and hot spring enthusiasts for its spectacular views of the waterfall while bathing.

Shomyo Falls has milky white water colored by hot spring minerals, and a bathtub is installed at its basin. The bathtub is about the size of a home bath, with hot spring water flowing in through a hose. The spring quality is sulfur-containing sodium/calcium-bicarbonate/sulfate/chloride spring, believed to be from the same source system as Tsubame Onsen. It's said to be effective for neuralgia, skin diseases, diabetes, hypertension, women's diseases, and burns.

As a complete wild hot spring, there are no facilities such as changing rooms - only the bathtub exists. Water volume and temperature vary depending on the season and weather, and sometimes the bath may not be filled. It's maintained by the Tsubame Onsen Tourism Association and is free to use. The operating period is from April 1st to early November, closed in winter (December to June) due to snow.

Access requires about 40-50 minutes of hiking from Tsubame Onsen parking lot, approximately 2 hours 15 minutes round trip. Hiking equipment is necessary, and extra caution is required during rainy weather or snow-melting season when the trail becomes slippery. Bathing while viewing the waterfall is exceptional, making this a must-visit hot spring for secret hot spring fans and hikers. While it's mixed bathing, visitor numbers are limited due to its remote mountain location.