A Gentle Hot Spring with a Distinctive Tradition
Kawarayu Onsen is classified as a salt-containing gypsum and hydrogen sulfide spring. The water is relatively gentle compared with the strongly acidic springs of Kusatsu Onsen and has traditionally been appreciated for its soft feel and warming sensation.
Two main spring systems are associated with the present hot spring: Moto-no-Yu, which preserves the traditional naturally emerging source, and Shin-Yu, a newer source developed through drilling.
The original natural source was protected during the construction of Yamba Dam and is now maintained through pumping. The newer source produces high-temperature water, and the heat is even used to prepare onsen tamago, or eggs gently cooked in hot spring water.
A Lakeside Foot Bath
A foot bath has also been provided near the spring area, allowing visitors to enjoy the warmth of the hot spring without taking a full bath.
The clear water has a subtle sulfur aroma, and the spring has traditionally been associated with relief from joint discomfort and other ailments. For this reason, Kawarayu has sometimes been called the “Hot Spring for the Joints.” Such descriptions reflect traditional hot spring culture rather than modern medical treatment.
The Relocation of the Hot Spring Town
The history of Kawarayu Onsen cannot be told without mentioning Yamba Dam.
The original hot spring town was located in the valley along the Agatsuma River. When the dam reservoir was created, the old town was submerged beneath the waters of the new lake.
Residents and hot spring businesses therefore relocated to higher ground on the southern side of the river, where a new hot spring district was developed.
The New Hot Spring Town
Today’s Kawarayu Onsen is spread across the elevated lakeside area. Several traditional inns and restaurants remain, allowing visitors to stay overnight while enjoying views of the lake and surrounding mountains.
The new town was designed around the concept of a hot spring district to explore on foot while enjoying the scenery. Public parking areas provide convenient starting points for walking through the neighborhood.
Bridges crossing the lake, broad mountain views, and the open sky create a very different atmosphere from the narrow river valley where the original town once stood.
The Former Hot Spring Town
The old Kawarayu Onsen was once a traditional hot spring settlement with inns lining the valley road. It had several communal bathing facilities, including Ōyu and Sasayu, as well as the mixed-gender Shōten-sama Open-Air Bath.
The town attracted many visitors seeking longer stays for hot spring bathing and rest. Today, however, the former town lies beneath the reservoir created by Yamba Dam, making the present lakeside district a symbol of Kawarayu’s dramatic transformation.
Ōyu — The Symbol of Kawarayu Onsen
Ōyu has long been regarded as the symbolic public bath of Kawarayu Onsen.
The original Ōyu closed on June 30, 2014. Just a few days later, on July 5, it reopened at its new location on higher ground as Ōyu Kaikan.
The facility has separate indoor and open-air baths. From the baths, visitors can look toward Lake Yamba Agatsuma and the surrounding mountains while experiencing the hot spring that has supported the community for centuries.
The high-temperature spring water also creates the distinctive local sight of eggs being cooked using the heat of the source. A nearby foot bath provides another easy way to experience Kawarayu’s hot spring culture while exploring the area.
A Hot Spring Tradition Dating Back to Minamoto no Yoritomo
The traditional founding story of Kawarayu Onsen dates to 1193.
According to local legend, the samurai leader Minamoto no Yoritomo was hunting in the area when he noticed steam rising from the ground. Following the steam, he discovered the hot spring.
The connection with Yoritomo is still represented at Ōyu, where the sasa-rindō, the crest traditionally associated with the Minamoto clan, can be seen.
The legend gives Kawarayu a strong connection with medieval Japanese history and contributes to its identity as a hot spring with a long samurai-era tradition.
The Legend Behind the YUKAKE Festival
Another famous story tells of a time, approximately 400 years after the hot spring was founded, when the spring suddenly stopped flowing.
According to local tradition, villagers investigated the source and noticed an unusual smell resembling boiled eggs. They prayed for the return of the hot spring and offered a chicken as a sacrifice.
The water eventually began flowing again, and this event is traditionally regarded as the origin of the Yukake Festival, one of Kawarayu’s most distinctive cultural traditions.
The Yukake Festival — A Unique Winter Tradition
The Yukake Festival is held in the early morning of January 20, during the coldest period of winter in Japan.
Traditionally, men wearing only loincloths divide into two teams and throw hot spring water at one another while shouting “Oiwai da, oiwai da!”, meaning roughly “It’s time to celebrate!” The expression is said to have evolved from an older phrase meaning “The hot water has returned!”
At the climax of the festival, a decorated ball containing a chicken is broken open. The person who catches the chicken is traditionally believed to receive good fortune.
The sight of participants throwing hot water into the freezing winter air creates an energetic and unforgettable spectacle. Visitors can also participate in the festival, making it a particularly immersive example of local Japanese hot spring culture.
Things to See Around Kawarayu Onsen
Yamba Dam and Lake Yamba Agatsuma
Yamba Dam is one of the major attractions in the area. From the dam itself and the nearby Yamba Miharashidai observation point, visitors can enjoy expansive views of the reservoir and surrounding mountains.
The landscape changes dramatically with the seasons, making the lakeside an attractive destination for photography and sightseeing.
Yamba Chaya
Located next to the dam museum, Yamba Chaya is a casual place to stop for food and drinks. Its terrace provides views of the lake, making it a pleasant spot to take a break while exploring the dam area.
Kawarayu Onsen Asobi no Kichi NOA
Kawarayu Onsen Asobi no Kichi NOA is an outdoor recreation facility on the shores of Lake Yamba Agatsuma.
Visitors can enjoy camping and barbecues without bringing all of their own equipment, as well as activities such as stand-up paddleboarding and kayaking. The facility also includes a bathing area known as Sasayu, where visitors can enjoy a hot spring bath.
Roadside Station Yamba Furusato-kan
Roadside Station Yamba Furusato-kan is a convenient stop for travelers exploring the region. Its market sells local specialties and fresh produce, while the restaurant is known for its distinctive dam curry, a curry dish arranged to resemble a dam and reservoir.
Yamba Tenmei Mudflow Museum
The Yamba Tenmei Mudflow Museum introduces the history of the 1783 eruption of Mount Asama and the devastating mudflows that followed.
Exhibits explain how the disaster affected villages and people’s daily lives, providing valuable historical context for understanding the landscape of the Agatsuma region.
Fudō Falls and Fudō Hall
Fudō Falls is a beautiful multi-tiered waterfall where visitors can view a section with a drop of approximately 40 meters.
A small hall dedicated to Fudō Myōō, a Buddhist deity associated with protection and spiritual strength, stands nearby. The site has long been connected with local religious traditions and continues to host annual ceremonies.
Kawarayu Shrine and Yakushidō
Kawarayu Shrine was newly established following the relocation of the hot spring community. During its annual festival, traditional Daidaikagura sacred dances are performed, preserving an important part of the area’s local culture.
A nearby Yakushidō, a Buddhist hall dedicated to Yakushi Nyorai, also reflects the long connection between Japanese hot springs and traditional healing beliefs.
Access to Kawarayu Onsen
From Kawarayu-Onsen Station on the JR Agatsuma Line, the hot spring district is approximately a 15-minute walk.
The walk itself is part of the experience, with views of Lake Yamba Agatsuma and the surrounding mountains along the way.
A Historic Hot Spring Reborn Beside a Lake
Kawarayu Onsen is a rare example of a Japanese hot spring town that has physically moved while preserving its historic identity.
The original settlement disappeared beneath the reservoir following the construction of Yamba Dam, but the community rebuilt itself on higher ground. Today, the new town combines 800 years of hot spring history with lakeside scenery, outdoor recreation, and traditional festivals.
Visitors can soak in the gentle spring water, walk through the new hot spring district, learn about the old town, explore Yamba Dam, and discover the legends and traditions that have been passed down through generations.
With its historic hot spring, dramatic relocation story, spectacular mountain scenery, and unique Yukake Festival, Kawarayu Onsen offers a fascinating glimpse into how a traditional Japanese community can adapt to profound changes while carrying its cultural heritage into the future.