A legendary hot spring with a long history
Kusatsu has been famous for centuries. During the Edo period (1603–1868), it was known as Kusatsu Village in Agatsuma District of Kozuke Province and was administered as part of the shogunate’s lands.
The resort became particularly famous for its exceptional volume of naturally flowing hot spring water. It is traditionally said to produce more than 32,000 liters of naturally flowing hot water per minute, one of the largest natural flows in Japan.
During the Muromachi period, the Zen monk and poet Bashō’s contemporary Banri Shūkyū recognized Kusatsu alongside Arima and Gero as one of Japan’s three great hot springs. In the Edo period, Confucian scholar Hayashi Razan similarly listed Kusatsu among the country’s three most celebrated hot spring resorts.
The name Kusatsu and its legends
The name Kusatsu has been used for centuries. Older poetic names such as “Kusatsu no Yu” and “Jōshū Kusatsu no Yu” were also used to describe the hot springs.
One theory suggests that the place name is connected with the strong sulfurous odor of the spring water, deriving from old Japanese expressions associated with “smelly water.” The exact origin of the name, however, remains a subject of historical interpretation.
Kusatsu is also surrounded by legends concerning its discovery. Stories attribute the opening of the hot springs to figures such as Prince Yamato Takeru, the Buddhist monk Gyōki, and Minamoto no Yoritomo. These stories are not firmly supported by historical evidence, but they have become an important part of Kusatsu’s cultural heritage and give the resort an enduring sense of mystery and romance.
A traditional reputation as a healing spring
The local Jōmō Karuta, a popular Gunma-themed card game, includes the phrase “Kusatsu, a good place with medicinal hot springs.” This reflects the area’s long-standing reputation as a place where people came to bathe and recuperate.
The famous expression that Kusatsu’s waters can cure almost any illness “except lovesickness” is a traditional saying rather than a modern medical claim. It reflects the exceptionally strong reputation that Kusatsu Onsen developed as a therapeutic bathing destination.
A volcanic landscape that creates powerful hot springs
Hot water shaped by volcanic activity
Behind the hot spring town rises the volcanic massif of Mount Kusatsu-Shirane, whose peaks reach more than 2,000 meters above sea level. The region’s volcanic activity provides the geothermal energy responsible for Kusatsu’s abundant hot spring water.
The springs are closely connected to groundwater and rainfall. Water moves underground, is heated by geothermal energy, and emerges through numerous natural sources. The chemical composition and acidity can vary depending on the source and its location.
Sources closer to the higher areas of the volcanic mountain can be particularly acidic, making Kusatsu an excellent destination for experiencing the dynamic relationship between volcanoes, groundwater, and hot springs.
Kusatsu’s exceptionally acidic hot spring water
Strongly acidic mineral-rich water
Kusatsu Onsen is famous for its strongly acidic hot spring water. Many of its sources have a pH of around 2.0, although the exact composition varies between individual sources.
The water contains sulfur and other minerals and has a distinctive aroma and sharp sensation on the skin. Its strong acidity has traditionally been associated with cleansing and antibacterial properties, and the springs have long been used as part of bathing practices for people seeking relief from various ailments.
Traditional descriptions of Kusatsu’s water often emphasize its use for conditions such as skin problems, cuts, neuralgia, muscle pain, and fatigue. However, these traditional claims should not be regarded as a substitute for medical treatment.
Take care when bathing
Because the water can be highly acidic and hot, visitors should bathe carefully. Those unfamiliar with strongly acidic hot springs should begin with a short bath and pay attention to how their skin and body respond.
It is also advisable to avoid bathing immediately after drinking alcohol or eating a large meal. Staying hydrated before and after bathing is especially important.
Yubatake: the symbol of Kusatsu Onsen
Steaming hot water at the heart of the town
Yubatake, meaning “Hot Water Field,” is the unmistakable symbol of Kusatsu Onsen. Located in the center of the resort, it is one of the most recognizable hot spring landscapes in Japan.
Approximately 4,000 liters of hot spring water per minute flows through the Yubatake area. The water passes through a series of long wooden channels, allowing it to cool naturally while its mineral components are exposed to the air.
This process produces a mineral deposit known as yunohana, or “hot spring flowers,” which has been collected and used as a local specialty since the Edo period.
A landmark designed with artistic vision
The present appearance of Yubatake was developed with the involvement of renowned Japanese artist Taro Okamoto. During the day, clouds of steam rise dramatically from the hot water. After sunset, illumination transforms the area into an atmospheric nighttime destination.
Yubatake has also received recognition as one of Japan’s notable soundscape and scenic destinations, and the area was designated as a Place of Scenic Beauty by the Japanese government in 2017.
The traditional atmosphere of Kusatsu’s hot spring town
Bathhouses, inns, restaurants, and souvenir shops
The streets surrounding Yubatake are filled with traditional inns, public bathhouses, restaurants, cafés, and souvenir shops. Steam rising through the streets creates the distinctive atmosphere of an old Japanese onsen town.
Today, Kusatsu is also actively developing its international tourism services, making it increasingly accessible to visitors from outside Japan.
Culture, nature, and recreation throughout the year
Kusatsu offers much more than hot springs. Visitors can enjoy cultural attractions such as the Kusatsu Music Forest International Concert Hall, wildlife and botanical experiences at Kusatsu Tropical Wonderland, and outdoor activities at Kusatsu Onsen Ski Resort.
The surrounding mountains and forests also offer seasonal attractions, from fresh greenery and flowers in spring and summer to colorful foliage in autumn and snowy landscapes in winter.
Kusatsu’s traditional bathing culture
Yumomi: cooling the hot spring water without adding water
Many Kusatsu springs emerge at temperatures of 50°C or higher, making the water too hot for ordinary bathing. One traditional solution is yumomi, a distinctive technique in which bath attendants stir the water with long wooden boards.
The boards are used to move and aerate the water while gradually lowering its temperature. Yumomi has become one of Kusatsu’s best-known cultural traditions and is performed for visitors at Netsu-no-Yu near Yubatake.
Time-yu: a traditional short bathing practice
Jikan-yu, or “time bathing,” is another traditional bathing practice associated with Kusatsu. It involves entering very hot spring water for a carefully controlled period.
The practice developed as part of Kusatsu’s therapeutic bathing culture. Because extremely hot water can place considerable stress on the body, the duration of bathing is strictly controlled in traditional practice.
Today, elements of this tradition continue as part of Kusatsu’s cultural heritage, although visitors should follow current instructions from qualified staff rather than attempting traditional high-temperature bathing on their own.
How to enjoy Kusatsu Onsen safely
1. Begin with kakeyu
Before entering a hot spring bath, gently pour some of the water over your body, starting with your feet and gradually moving upward. This helps your body adjust to the heat.
2. Keep your first bath short
If you are unfamiliar with hot springs, especially strongly acidic springs, start with approximately 3–5 minutes and leave the bath if you feel uncomfortable. Longer bathing is not necessarily better.
3. Rinse according to your skin’s needs
Some bathers prefer not to rinse immediately after bathing in order to retain the sensation of the mineral-rich water. However, people with sensitive skin may wish to rinse gently with fresh water. Follow the guidance provided at each facility.
4. Drink plenty of water
Kusatsu is located at high elevation, and bathing in hot water can contribute to dehydration. Drink water before and after bathing, particularly during winter or after spending time outdoors.
Kusatsu as a traditional hot spring therapy destination
The Japanese culture of tōji
Kusatsu developed not only as a bathing resort but also as a destination for tōji, the traditional Japanese practice of staying at a hot spring resort for an extended period while bathing and resting.
During the Edo period, visitors could stay for days or weeks in simple accommodations and prepare their own meals while following a regular bathing routine. Kusatsu became particularly well known as a destination for people seeking relief from chronic ailments and skin conditions.
Erwin von Baelz and the international recognition of Kusatsu
During the Meiji period, German physician Erwin von Baelz studied and promoted the therapeutic potential of Japanese hot springs, including Kusatsu. His work helped introduce Kusatsu to a wider international audience and contributed to the development of modern hot spring research in Japan.
Today, visitors generally come to Kusatsu for relaxation, recreation, and cultural experiences rather than medical treatment. The traditional concept of tōji, however, continues in a modern form through shorter stays focused on rest and well-being.
Kusatsu’s many natural hot spring sources
The principle of using the original spring water
Kusatsu is famous for its abundant natural spring water and its emphasis on using the water from its original sources. Many facilities use the spring water with little or no added fresh water, allowing visitors to experience the distinctive mineral characteristics of each source.
Some springs emerge at temperatures approaching 90–95°C. Such water must be cooled or heat-exchanged before it can be used for bathing.
Yubatake Source
The Yubatake Source is one of Kusatsu’s most famous springs. Approximately 4,000 liters of water per minute emerge from the source, with temperatures around 50°C. The water flows through wooden channels, where it naturally cools and produces yunohana.
Water from this source is supplied to numerous inns and public bathhouses around the town.
Shirahata Source
The Shirahata Source is known for its slightly milky appearance, strong acidity, and distinctive sulfurous aroma. Its pH is around 2.1, making it one of the strongly acidic sources in Kusatsu.
A traditional legend associates the source with Minamoto no Yoritomo, who is said to have bathed here during the Kamakura period. The nearby Shirahata-no-Yu public bath allows visitors to experience this historic source.
Sainokawara Source
The Sainokawara Source emerges in a dramatic volcanic landscape that is now part of Sainokawara Park. The park is known for its streams of hot water, steaming ground, and large open-air bath.
The combination of natural scenery and hot spring water makes this one of the most atmospheric places to experience Kusatsu’s volcanic environment.
Bandai-Kō Source
The Bandai-Kō Source is one of Kusatsu’s most powerful hot spring sources. It emerged from a sulfur mine in 1970 and produces extremely hot water, reaching approximately 95°C.
Because the water is too hot for direct bathing, its temperature is adjusted through heat-exchange systems before being distributed to accommodations and other facilities. The heat is also used for purposes such as road snow melting and heating, demonstrating how Kusatsu makes practical use of its geothermal resources.
Jizō Source
The Jizō Source is located near Jizō-do Hall and is traditionally regarded as having a relatively gentle feel compared with some of Kusatsu’s other springs. The nearby Me-arai Jizō statue is associated with traditional beliefs concerning eye health.
The source is also used in facilities such as foot baths, making it an easy way to experience Kusatsu’s hot spring water.
Nikawa Source
The Nikawa Source is a distinctive spring used by Otaki-no-Yu. Its water is another example of the variety found among Kusatsu’s different natural sources.
Discover the differences between Kusatsu’s hot springs
Source-hopping as part of the Kusatsu experience
Because Kusatsu has numerous natural sources, the temperature, mineral composition, aroma, and sensation of the water can differ from one bathing facility to another.
Trying different baths is therefore one of the pleasures of visiting Kusatsu. You can experience the classic atmosphere of the Yubatake Source, the strong character of Shirahata, and the open-air setting of Sainokawara while discovering how each source has its own personality.
Public bathhouses and local bathing culture
Kusatsu has traditionally maintained numerous community bathhouses. Several public baths are available to visitors, including Shirahata-no-Yu, Jizō-no-Yu, and Chiyo-no-Yu.
These baths provide an opportunity to experience the same hot spring culture that has long been part of everyday life for local residents. Visitors should remember that public bathhouses are shared community spaces and should follow local bathing etiquette.
A town shaped by its hot springs
In Kusatsu, the hot springs are much more than a tourist attraction. They have shaped the town’s streets, architecture, culture, economy, and daily life.
The steam rising around Yubatake and other sources creates a landscape that is uniquely associated with Kusatsu. The enormous volume of spring water has also supported a tradition of public baths and foot baths that are free or inexpensive in many locations.
The result is a hot spring town where visitors and residents can experience the same natural resource at the heart of the community.
The long history of Kusatsu Onsen
Ancient and medieval legends
The origins of Kusatsu Onsen are surrounded by legends involving Prince Yamato Takeru, Gyōki, and Minamoto no Yoritomo. Although these stories cannot be conclusively confirmed as historical fact, they form an important part of the resort’s traditional identity.
The name Kusatsu appears in historical records by the Muromachi period. By that time, the hot springs were already famous enough to be counted among Japan’s great hot spring destinations.
The Warring States period
During Japan’s Warring States period, the surrounding region was contested by powerful clans including the Uesugi, Takeda, and Sanada families.
Despite political changes, Kusatsu continued to develop as a bathing and recuperation destination. Under the Sanada family’s influence, the management and protection of the hot springs were further organized.
The Edo period: a nationally renowned hot spring
During the Edo period, Kusatsu became part of the shogunate’s directly administered lands. Its reputation spread throughout Japan, and increasing numbers of visitors traveled long distances to stay for hot spring therapy.
Travel from Edo, present-day Tokyo, could take several days on foot, yet Kusatsu attracted large numbers of visitors. The prosperity of the resort was reflected in the saying “Kusatsu Senken Edo-gamae,” which described a bustling town with a thousand houses arranged in the style of Edo.
This period also saw the development and refinement of distinctive bathing practices such as yumomi and time-yu.
The Meiji period: the meeting of hot springs and modern medicine
After the Meiji Restoration, Western medicine was introduced to Japan, and Japanese hot springs began receiving greater scientific attention.
Erwin von Baelz was particularly influential in introducing the qualities of Kusatsu Onsen to audiences outside Japan. His research and advocacy helped establish Kusatsu as an internationally recognized hot spring resort.
The Taishō and Shōwa periods: development as a tourist destination
As Japan’s transportation network improved, Kusatsu became increasingly accessible. Railways and bus services brought growing numbers of visitors who came not only for therapeutic bathing but also for sightseeing and leisure.
During the Shōwa period, the town’s inns, shops, and tourist facilities expanded. The development of the ski resort also helped establish Kusatsu as a destination that could be enjoyed throughout the winter.
From the Heisei period to the present
In more recent decades, the area around Yubatake has undergone improvements to its landscape, infrastructure, and visitor facilities. Nighttime illumination has transformed Yubatake into a particularly popular evening attraction.
Kusatsu has also introduced new facilities and services for international visitors, while continuing to preserve traditional bathing culture.
Experience one of Japan’s great hot spring towns
Kusatsu Onsen brings together abundant natural hot spring water, strongly acidic mineral-rich springs, volcanic landscapes, centuries of history, and a beautifully preserved onsen-town atmosphere.
Visitors can stroll around the steaming Yubatake, watch the traditional yumomi performance, explore historic public baths, enjoy an outdoor hot spring surrounded by nature, and experience the distinctive atmosphere of a Japanese hot spring resort.
For international travelers interested in Japanese culture, nature, and traditional bathing, Kusatsu offers an opportunity to experience how hot springs have influenced Japanese life for centuries.
Exploring Gunma Prefecture
Beyond Kusatsu and Shima, Gunma Prefecture offers a wide variety of destinations, including Shibukawa and Ikaho, Tatebayashi and Ōta, Takasaki and Maebashi, Tomioka and Shimonita, Oze and Numata, Kiryu and Akagi, and Minakami.
Travelers can explore historic temples and shrines, castles, traditional streets, museums, gardens, mountains, wetlands, waterfalls, lakes, hot springs, ski resorts, local food, agricultural experiences, sake breweries, and scenic driving routes.
Kusatsu Onsen is an excellent starting point for discovering the broader natural and cultural attractions of Gunma and the Kanto region.