Bathing in Harmony with the Seasons
One of the greatest attractions of Sainokawara Open-Air Bath is the opportunity to experience the changing seasons at close range.
From spring into early summer, fresh green leaves create a vivid backdrop while the crisp mountain air adds to the refreshing atmosphere. In autumn, the surrounding trees turn shades of red, orange, and gold, and their reflections on the surface of the hot spring create a beautiful scene.
Winter offers another special experience: yukimi-buro, or “snow-viewing bath”. Visitors can soak in the warm water while watching snow fall across the surrounding landscape, an experience strongly associated with traditional Japanese hot spring culture.
After dark, parts of Sainokawara Park are illuminated, creating a completely different atmosphere from daytime. The lights catch the rising steam, while the surrounding darkness makes the night sky particularly impressive.
The Powerful Bandai Hot Spring
The open-air bath uses water from the Bandai Source, one of the major hot spring sources of Kusatsu Onsen.
The source water emerges at an exceptionally high temperature of approximately 94–95°C. The spring is classified as an acidic chloride-sulfate spring, with a pH of approximately 1.7.
Kusatsu’s strongly acidic hot spring water has traditionally been valued for its cleansing and bathing properties. It has long attracted visitors seeking the benefits of toji, the traditional Japanese practice of spending an extended period at a hot spring resort for rest and recuperation.
Traditional descriptions of the spring’s benefits include relief from conditions such as neuralgia, joint pain, bruises, burns, chronic digestive disorders, recovery after illness, and certain gynecological conditions. Such descriptions reflect the historical use of hot springs and should not be regarded as modern medical treatment.
A small cascade of hot spring water flows into the large bathing area, allowing visitors to appreciate the abundant flow of the source.
There are no washing stations inside the open-air bath, so visitors normally rinse themselves with hot spring water before entering the main bath. Separate changing rooms, lockers, and toilets are provided for men and women.
A Magical Atmosphere After Dark
Sainokawara Park is illuminated from around sunset into the evening, giving the area a mysterious and atmospheric appearance.
The steam rising from the hot spring water becomes softly illuminated, creating a striking contrast with the surrounding darkness. For visitors using the open-air bath at night, the experience of relaxing in warm water while looking up at the stars can become one of the memorable moments of a Kusatsu trip.
Friday Is “Mixed Bathing Day”
On Fridays, except on designated special dates, Sainokawara Open-Air Bath holds a special “Mixed Bathing Day.” During a designated period in the evening, the men’s open-air bath becomes available for mixed-gender bathing.
This provides couples, married couples, and families with an opportunity to enjoy the hot spring together. To make the experience more comfortable, special bathing clothes are available for both men and women, with rental bathing attire provided for female visitors.
The combination of bathing together and the illuminated scenery around the park creates a distinctive evening experience. Visitors should check the current schedule and conditions before planning their visit, as the arrangement is subject to designated dates and times.
Sainokawara Park and a Natural Hot Spring Landscape
The open-air bath is located within Sainokawara Park, an area designated as a special zone of Joshin’etsukogen National Park.
The park is approximately a 10- to 15-minute walk from Yubatake, the central symbol of Kusatsu Onsen. Along the walking route, visitors encounter steaming streams and pools of naturally heated water before reaching the spectacular landscape of Sainokawara.
Hot spring water emerges from numerous places across the broad riverbed, with the total flow reaching approximately 1,400 liters per minute. The water forms small waterfalls and pools before flowing together as a hot spring stream.
The landscape gives visitors a vivid impression of the geothermal activity beneath Kusatsu.
Legends of Demons and the Power of the Earth
The area was once known as “Oni no Sensui,” or “Demon’s Spring Water,” because the mysterious steam and boiling water were associated with stories of demons living in the area.
Several places connected with these legends remain around the park, including Oni no Chagama (“Demon’s Tea Kettle”) and Oni no Sumojo (“Demon’s Sumo Ring”).
With hot water emerging directly from deep within the earth and white steam drifting across the landscape, Sainokawara retains a mysterious atmosphere that has inspired both local legends and reverence for the power of nature.
Things to See Around Sainokawara Park
The area surrounding Sainokawara Park contains numerous places of historical, cultural, and religious interest.
Near the entrance to the park are monuments and statues associated with the history of Kusatsu Onsen. Busts of Dr. Erwin von Baelz and Dr. Julius Scriba, German physicians who contributed to the development and international recognition of modern medicine in Japan, can also be found here.
Other points of interest include Kusatsu Anamori Inari Shrine, Enmusubi Jizo associated with relationships and matchmaking, Fudotaki Waterfall, and Mizuko Jizo, a Buddhist figure associated with the remembrance of unborn children.
A monument to the poet Mokichi Saito also stands in the area, with a poem he composed in Kusatsu engraved on it.
Nature changes dramatically throughout the year. Marsh marigolds and azaleas bloom in spring, the sound of cicadas fills the area in early summer, autumn brings colorful foliage, and winter transforms the park into a snowy landscape.
Enjoy Kusatsu with the Three-Bath Pass
Visitors who want to experience several different sides of Kusatsu’s bathing culture can take advantage of the Three-Bath Pass, which allows access to three major day-use hot spring facilities: Sainokawara Open-Air Bath, Otaki-no-Yu, and Gozanoyu.
Each facility has its own atmosphere and uses different hot spring sources, allowing visitors to compare the character of Kusatsu’s famous waters.
Those who complete all three baths can also receive a “Three-Bath Master” certificate, adding a playful challenge to a Kusatsu hot spring trip.
Otaki-no-Yu
Otaki-no-Yu is another major day-use hot spring facility in Kusatsu and offers a different style of bathing from the enormous open-air bath at Sainokawara.
It uses the Nikawa Source, one of the six major hot spring sources of Kusatsu, which has traditionally been known as a “beauty-enhancing spring.”
The Traditional “Awase-yu” Bathing Method
The highlight of Otaki-no-Yu is its traditional Awase-yu bathing system.
Instead of cooling the source water by adding ordinary water, the hot spring water passes through a series of baths and gradually cools naturally. The first bath is the coolest, while the temperature becomes progressively higher as visitors move farther through the sequence.
The traditional approach is to begin with the cooler bath and gradually allow the body to adjust before moving into hotter water.
Separate Awase-yu areas are provided for men and women. The combination of rising steam and the strongly mineral-rich hot spring water creates a distinctly traditional Kusatsu bathing atmosphere.
Gozanoyu
Gozanoyu stands directly in front of Yubatake and is a day-use hot spring facility modeled on the public bathhouses that existed in Kusatsu during the Edo and Meiji periods.
The building uses traditional wooden construction, including a distinctive wooden roof and plaster walls, recreating the atmosphere of an earlier era.
Two Bathing Areas and Two Hot Spring Sources
Inside are two bathing areas known as Kino-yu and Ishi-no-yu. The men’s and women’s areas alternate between the two on different days.
Kino-yu and Ishi-no-yu each use a different hot spring source: Yubatake Source and Bandai Source. Visitors can therefore experience differences in the character of the water while enjoying two contrasting bathing environments.
One bath emphasizes the warmth and atmosphere of wood, while the other features substantial granite bathing tubs. Together, they offer an introduction to the bathing culture that has developed around Kusatsu’s abundant hot spring resources.
Explore the Hot Spring Town in a Yukata
Gozanoyu also offers rental yukata, traditional lightweight Japanese summer robes that can be worn while walking around the hot spring town.
Strolling around Yubatake and the surrounding streets in a yukata, with steam rising from the hot springs, creates an atmosphere that can feel like stepping back into an earlier period of Japanese history.
A Hot Spring Experience Surrounded by Four Seasons of Nature
The greatest attraction of Sainokawara Open-Air Bath is its extraordinary scale and sense of connection with the surrounding landscape.
Fresh greenery, autumn foliage, and snow-covered scenery each provide a completely different setting for bathing. Rather than being surrounded by buildings, visitors can relax while looking directly at the mountains and sky.
The area also offers a quieter atmosphere than the busy center of Kusatsu Onsen, making it an ideal place to slow down and appreciate the natural side of the resort.
For travelers visiting Kusatsu Onsen, a bath at Sainokawara is an opportunity to experience the remarkable combination of Japan’s hot spring culture, powerful geothermal activity, and beautiful mountain scenery.