Sainokawara Rotenburo

Bathe in Nature at
Sainokawara Rotenburo

Recharge at Kusatsu Onsen!

Having spent a day in the great outdoors, it is time to relax in one of Kusatsu’s natural hot spring baths, commonly known as onsen.

Bathing has been a major part of Japanese culture since antiquity, and Kusatsu Onsen’s baths are a fantastic chance to dip your toe (and more!) into this essentially Japanese cultural experience. Do not just take our word for it either—Japan’s major travel agents have voted Kusatsu Onsen the number-one onsen in Japan for over sixteen years in a row.

The bountiful waters drawn directly from the Yubatake hot spring fields naturally contain acid, sulfur-containing aluminum sulphate, and chloride, with pH values between 1.7 and 2.1, and temperatures varying between 51 and 94 degrees Celsius. An iron nail placed in the hot spring would be reduced to rust in just nine days. But do not worry, the centuries-old yumomi method of cooling the water makes it perfectly safe for everyone to enjoy, and the accompanying ceremony is now a local attraction, with regular demonstrations enlivened by folk songs.

The rich mineral content of Kusatsu’s waters have become known for their metabolism-boosting effects and as a natural way to promote more beautiful skin. The hot springs are also said to be beneficial for a variety of conditions, including muscle pain, bruises and sprains, fatigue recovery and more. Said to cure basically everything except lovesickness, you are bathing in good company—even the leaders of the Tokugawa shogunate during the Edo period (1603–1867) ordered barrels of hot spring water to be delivered to Edo Castle.

Take a deeper look into three of Kusatsu Onsen’s
famed hot spring baths.

Sainokawara Rotenburo

For an especially indulgent experience as you bask in nature, explore Sainokawara Rotenburo, a 500-square meter open-air bath surrounded by forest views. Each season offers a different view—snow-capped trees in winter, cherry blossoms in spring, deep green in summer, and vibrant reds, yellows, and orange in autumn.

A short twelve-minute stroll from the Yubatake hot water fields in the center of Kusatsu town brings you to Sainokawara Rotenburo, for a truly natural outdoor onsen experience.

The large outdoor bath (rotenburo) is separated for men and women, and at 500 meters square can comfortably accommodate up to one hundred people at a time, making this a good choice for larger groups. Fed by the Bandai hot water springs containing acidic chloride sulphate, and recommended for conditions including chronic digestive diseases and recovery from illness, the vast bath also features a hot waterfall-like cascade.

Sainokawara Rotenburo can be enjoyed at any time of year, and the four seasons provide a rotating backdrop to the baths. On clear nights, you can enjoy stargazing, while the changing autumn leaves bring a touch of vibrant colors to the experience. In winter, soaking in the hot waters of the bath under a gentle snowfall is unforgettable.

Although located just a short walk from Kusatsu Onsen town center, Sainokawara Rotenburo is very much part of the countryside of the area. A stone-paved promenade leads visitors along a winding path past a variety of popular sightseeing spots including Anamori Inari shrine, the Oni no Chagama monument, Matchmaking Jizo (a series of Buddhist statues which are said to be protectors of children and travelers), and the Kusatsu Visitor Center. This easy path is a good introduction to the natural beauty of the surrounding area. Not only can you immerse yourself in the healing waters of the outdoor bath but also in the history and culture of Kusatsu.

On your walk, be sure to seek out the busts of German physicians Dr Erwin Bälz and Dr Julius Scriba, local heroes of Kusatsu Onsen who were instrumental in expounding the healing virtues of the hot springs in Japan and abroad.

Sainokawara Rotenburo also offers an evening of mixed bathing every Friday, when the bath is open to everyone, including couples and families. During the mixed bathing evenings visitors can wear swimwear or wrap themselves in a towel, a chance to enjoy the full onsen experience together.

Opening hours: April 1st–November 30th 7:00 am–8:00 pm (entry closes at 7:30 pm), Dec 1st–March 31st 9:00 am–8:00 pm (entry closes at 7:30 pm)
Prices: Adults 800 Yen, children 400 Yen (ages 3–12)
Inquiries: Oazakusatsu 521-3, Kusatsu Town, Agatsuma County, Gunma Prefecture 377-1711
Tel: 0278-88-6167

Into Enchanted Waters Beloved
Since Antiquity

Torrents of milky blue waters descend from the volcanic peaks of Mount Shirane and burst into Kusatsu Onsen’s Yubatake onsen fields, creating clouds of steam that cover the town in a misty haze. This boiling water is then tamed by a centuries-old system of stirring the waters using paddles, in a ceremony called yumomi; cooling it just enough for visitors to take a dip and enjoy the therapeutic benefits of the hot springs.

Considered to be one of Japan’s three most important onsen resorts, Kusatsu boasts so many bathing facilities you’ll be spoiled for choice.

The hot spring’s curative effects are also the stuff of legend. It is said that the waters at Kusatsu Onsen are able to cure any illness but lovesickness. The town’s hot springs are also unrivaled in quantity, boasting the largest output of natural hot spring waters in Japan. With over 32,000 liters gushing out per minute, the waters do not need to be diluted or reheated. High in acidity, bacteria and fungi cannot survive in these piping hot waters, giving it an antibacterial effect that has furthered the belief in the hot springs’ therapeutic effects over the centuries.

Immerse Yourself
in Centuries-Old Bathing Tradition

As one of Japan’s three most famous hot spring resorts, Kusatsu boasts a vibrant traditional onsen town atmosphere so you can experience centuries of Japanese tradition and culture intertwined with the hot springs.

Between baths, stroll down the town’s main street basking in the retro romance as you browse shops laden with local souvenirs, glassware crafts, and more. Drop by one of the many charming confectionary shops to sample tasty wagashi sweets that have been steamed in the therapeutic waters. Enjoy these warm, sweet buns as you stroll the narrow streets around the town, taking in the historic buildings swathed by swirling steam, a sight all the more remarkable when illuminated at night.

To make your visit even more authentic, rent a yukata at Gozanoyu and don it for your outing. A dressing service is available and you do not need to prepare anything yourself! Circle Yubatake and be enveloped in steam as you take in the view of milky blue waters gushing forth through the old pinewood tubs. Free footbaths let you to rest your feet while you enjoy the scenery.

Enjoying Your Visit!

To discover more of the wonders that await you at Kusatsu Onsen, be sure to explore the rest of this website. Here, you’ll find countless tips on where to eat, drink, and stay to find the perfect spots for your visit to Japan’s original resort town. There are also sightseeing suggestions for areas around the town to make the most of your stay here, and examples of popular souvenirs for that special someone at home. If you want to know more about Japanese bathing customs, there is a step-by-step guide available on the website, as well as plenty of information upon arrival to guarantee you turn into an onsen pro.

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Attention of the bathing

To make sure you enjoy the baths safely, although the baths have therapeutic effects, it is important to note that your body will sweat more while enjoying them, perhaps more than you may realize. Drink plenty of water between baths to stay hydrated—which you can do with Kusatsu’s own natural mineral waters for an extra dose of well-being. Also, the acidity of some of the waters at Kusatsu Onsen is strong enough to cause silver to develop an instant patina, so be sure to remove all your jewelry before you bathe.

Finally, for guests from overseas, rest assured that the vast majority of Kusatsu Onsen inns and bath facilities are welcoming to those with non-gang-related body art. Travelers with tattoos can enjoy the healing hot waters here without any worries, and join the approximately three million annual visitors to this world-class hot spring resort.

We welcome you to Kusatsu Onsen,
and we are sure you will be back time and time again!