Shirahone Host Spring Public Open-air Bath is located in Azumi, Matsumoto City, Nagano Prefecture, at the foot of Mt. Norikura in the Northern Japan Alps, at an elevation of approximately 1,400 meters within the Chubu Sangaku National Park. This rustic open-air bath is built along the Yukawa mountain stream, providing a day-use public bathing facility conveniently located near the Shirahone Onsen Tourist Information Center.

The history of Shirahone Onsen dates back to the Kamakura period (around 1185-1333), with over 600 years of documented history. Legend has it that during the Sengoku period, the warlord Takeda Shingen used these waters as a "hidden hot spring" (kakushi-yu) to heal wounded soldiers and miners. During the Genroku period of the Edo era (1688-1703), Saito Magoemon formally established the first hot spring inns, attracting visitors seeking therapeutic treatments.

In the Taisho era, the hot spring gained nationwide recognition when writer Kaizan Nakazato praised it as a "magnificent and colorful scenic beauty" in his epic novel "Daibosatsu Pass." The renowned poet Wakayama Bokusui also frequented the springs numerous times for treatment of his stomach ailments, leaving behind many literary works inspired by the location.

Shirahone Onsen is famous for the saying "Bathe for three days, and you won't catch a cold for three years," particularly known for its effectiveness in treating gastrointestinal disorders. The distinctive milky white water emerges clear from the source but transforms into a beautiful cloudy white color as hydrogen sulfide and calcium components react with air exposure. This unique phenomenon creates different appearances daily based on water composition, temperature, and seasonal changes, leading locals to describe the waters as "living beings."

The public open-air bath features gender-separated stone baths with the mountain stream flowing nearby, creating an immersive natural environment. The scenery is particularly stunning during fresh green spring and autumn foliage seasons. Among Shirahone's day-use facilities, this bath accommodates the largest number of visitors. With free-flowing source water, the sulfur aroma and silky-smooth texture create an authentic hidden hot spring experience.