Nikawa Hot Spring — The “Beauty Bath”
One of the greatest attractions of Otaki-no-yu is its use of the Nikawa hot spring source. Among Kusatsu’s many natural hot spring sources, Nikawa is particularly valued for its distinctive properties.
The source is a hot, acidic sulfur spring with a pH of approximately 2.1. It has a smooth feel on the skin and is traditionally known as a “beauty bath.”
Kusatsu’s strongly acidic hot spring water has long been appreciated for its cleansing properties, and historically the baths were associated with hot spring treatment for various ailments. Today, visitors should regard these descriptions as part of the historical culture of Kusatsu rather than as medical claims.
Natural-Flow Hot Spring Water
At Otaki-no-yu, the Nikawa source is used without dilution with ordinary water. Instead, the water is allowed to cool naturally before flowing directly into the baths.
Fresh hot spring water continuously enters the bathing pools, while used water flows out rather than being recirculated. This traditional gensen kakenagashi system allows visitors to experience the hot spring water in its natural state.
Experience Kusatsu’s Traditional “Awase-yu”
The centerpiece of Otaki-no-yu is Awase-yu, a traditional Kusatsu bathing method. The hot spring water is allowed to cool naturally as it flows through a series of bathing pools, creating different temperatures along the way.
Gradually Acclimatize to the Heat
The traditional method is to begin with the cooler pool and gradually move to pools with hotter water. This allows bathers to become accustomed to the intense temperature step by step.
Because the water is not diluted, the distinctive character of Kusatsu’s hot spring water remains strong. Moving between pools of different temperatures is an enjoyable way to experience one of the area’s unique bathing traditions.
Distinctive Bathing Spaces for Men and Women
The men’s Awase-yu area has a atmospheric, steam-filled design, with the appearance of the mineral-rich water changing subtly depending on the temperature. It contains five bathing pools, allowing visitors to experience different stages of the traditional bathing process.
The women’s Awase-yu area has a more elegant design incorporating Western-inspired decorative elements. It also provides convenient access from the changing area and open-air bath, creating a calm setting for enjoying the traditional bathing experience.
Spacious Indoor and Open-Air Baths
A Large, Open Indoor Bath
The spacious indoor bathing area has a high ceiling and an open atmosphere. The baths are large enough for visitors to stretch out and relax.
The washing area is equipped with showers, shampoo, and body soap. There is also a waterfall-style bath, where falling hot spring water provides a pleasant sensation against the body.
An Impressive Hot Spring Waterfall
Stepping outside from the main bathing area reveals one of Otaki-no-yu’s most memorable features: a large hot spring waterfall.
Hot spring water cascades down like a natural waterfall, creating a dramatic view and a strong sense of connection with the surrounding landscape. Bathing outdoors while feeling the changing air of each season is one of the great pleasures of visiting a Japanese hot spring.
Sauna and Relaxation
Otaki-no-yu also features a traditional sauna maintained at approximately 92–96°C (198–205°F). Combining time in the sauna with bathing can provide a refreshing relaxation experience.
Special “White Water Day”
On the second and fourth Saturdays of each month, Otaki-no-yu holds a special event known as “White Water Day.”
The normally clear Nikawa hot spring water becomes cloudy as yunohana, naturally occurring mineral deposits commonly called “hot spring flowers,” enter the water during maintenance work on the distribution pipes.
The result is a milky, sulfur-scented bath that offers visitors a chance to experience a different appearance and atmosphere from the usual Nikawa source.
Private Baths and Other Facilities
Private Bath “Shakunage”
For families, couples, or visitors who prefer a private setting, Shakunage is a private bathing facility available for personal use.
The bath can be reserved for one hour for ¥2,000, with no specified limit on the number of users within the permitted capacity. It provides a comfortable way to enjoy Kusatsu’s hot spring water in a more private environment.
Restaurant “Yunohana”
The on-site restaurant serves dishes made with ingredients from Gunma Prefecture.
Popular choices include tsuke-himokawa udon made with Joshu Mochi Pork and ramen featuring Joshu chicken. These hearty local dishes are especially satisfying after a relaxing bath.
Lounge and Rest Areas
The lounge café provides a comfortable place to relax in rattan chairs. Popular refreshments include Kusatsu Onsen Cider and freshly ground coffee.
A spacious free rest area is also available in the basement, where visitors can take a break after bathing.
Souvenirs and Original Products
The facility’s shop offers a variety of souvenirs, including the local specialty Kusatsu Mochi, original Otaki-no-yu bath additives, and cosmetics containing hot spring water.
The original bath additives are particularly popular with visitors who want to recreate a little of the Kusatsu hot spring experience at home.
Barrier-Free Facilities
The interior features warm wooden elements and is designed to provide a comfortable environment for a wide range of visitors. Except for the basement area, the facility is equipped with barrier-free access, making it easier for visitors with mobility needs to use the facility.
Explore Kusatsu with the Three-Bath Pass
Visitors who want to experience more of Kusatsu’s bathing culture can use the “Three Baths Tour Pass”, which allows them to visit three major day-use hot spring facilities: Otaki-no-yu, Gozano-yu, and Sainokawara Open-Air Bath.
Each facility offers a different atmosphere and different hot spring sources, making the three-bath experience a convenient way to discover the variety of Kusatsu’s bathing culture.
Visitors who complete all three baths can also receive a “Three Baths Tour Master” certificate, adding a fun goal to a Kusatsu hot spring trip.
Gozano-yu
A Recreated Historic Communal Bath
Located directly in front of the famous Yubatake, Gozano-yu is a day-use hot spring facility recreating a communal bathhouse that existed in Kusatsu during the Edo and Meiji periods.
The building was designed with traditional wooden construction in mind. Its wood-shingled roof and plaster walls evoke the atmosphere of historic Kusatsu and give visitors a sense of the town’s traditional architectural character.
Two Bathing Areas and Two Hot Spring Sources
Inside are two bathing areas called Kino-yu and Ishi-no-yu. The men’s and women’s areas alternate between them each day.
The baths use two different natural hot spring sources, Yubatake Source and Bandai Source, allowing visitors to experience the subtle differences between Kusatsu’s spring waters.
One bathing area features the warmth of wood, while the other uses substantial granite tubs. Each has its own character and atmosphere.
Stroll Around Kusatsu in a Yukata
Gozano-yu also offers rentals of yukata, traditional lightweight Japanese summer robes. Visitors can put on a yukata and stroll around the Yubatake area and surrounding hot spring town.
Walking through the steam-filled streets in traditional clothing can create the feeling of stepping back into the atmosphere of historic Japan.
Sainokawara Open-Air Bath
Located in the nature-rich western part of Kusatsu, Sainokawara Open-Air Bath is another famous bathing destination. It is approximately a 10–15-minute walk from Yubatake, the center of Kusatsu’s hot spring town.
Following the stone-paved streets through rising steam, visitors eventually reach an enormous open-air bath surrounded by forest.
The combined bathing area for men and women covers approximately 500 square meters, with around 333.5 square meters for the men’s bath and 166 square meters for the women’s bath. The spacious bath can accommodate approximately 100 people at once.
Surrounded by woodland and highland scenery, the large open-air bath provides a remarkable sense of space. Bathing while feeling the changing seasons of the mountain environment is one of the defining experiences of Kusatsu.
Interesting Facts About Kusatsu Onsen
Kusatsu Onsen is traditionally counted among Japan’s Three Famous Hot Springs, alongside Arima Onsen and Gero Onsen.
The area has long been associated with hot spring therapy, and an old saying claims that Kusatsu’s waters can cure almost every illness except “lovesickness.”
An Extraordinary Volume of Hot Spring Water
Kusatsu is famous for its enormous natural discharge of hot spring water, traditionally estimated at more than 36,000 liters per minute.
That is roughly equivalent to the volume of 184 standard Japanese drums every minute. The abundant natural supply makes it possible for Kusatsu to continuously provide fresh spring water without relying on recirculation.
The Strong Acidity of Kusatsu’s Springs
Many of Kusatsu’s hot springs are strongly acidic, with a pH of around 2. The water is known for its powerful cleansing and antimicrobial properties, which have contributed to the area’s reputation throughout history.
The intensity of the water is one of the characteristics that distinguishes Kusatsu from many other hot spring destinations in Japan.
A Highland Resort for Every Season
Located at an elevation of approximately 1,200 meters, Kusatsu enjoys relatively cool summers and has long been known as a highland retreat.
In winter, the area becomes a popular ski destination, while the hot springs and surrounding natural scenery make Kusatsu an attractive destination throughout the year.
Experience the Famous Hot Springs of Kusatsu
Traditional Awase-yu bathing, dramatic open-air baths, abundant natural hot spring water, and extensive facilities come together at Otaki-no-yu.
Whether you stop by between sightseeing activities or spend several hours relaxing in the baths, Otaki-no-yu offers an excellent introduction to the distinctive hot spring culture of Kusatsu.
For visitors exploring Kusatsu Onsen, soaking in its strongly acidic natural hot spring water while learning about traditional bathing customs is a memorable way to experience one of Japan’s most famous hot spring towns.