Bathe like royalty and experience the local longtime tradition of yumomi.
The healing power of Kusatsu Onsen is so treasured that Japan’s first, eighth and 10th shoguns had its thermal water shipped all the way to Tokyo so they could bathe in it. The revered hot spring area in Gunma Prefecture is located just two and a half hours from Tokyo by car.
This hot spring mecca is one of Japan’s three most famous onsen towns along with Gero and Arima Onsen. Kusatsu owes its reputation to the immense quality and quantity of its healing spring water. The acidity is strong enough to kill bacteria on contact as well as treat inflammation.
White rocks on the mountaintop and the emerald green water of Lake Yugama feel otherworldly.
In Kusatsu, there’s a unique type of hot spring with water sourced from a hot crater lake called Lake Yugama. You’ll find it 1,2000 meters above sea level on top of Mount Shirane (also known as Mount Kusatsu-Shirane). It’s only 30 minutes away from the main tourist area by bus, so definitely add it to your itinerary.
With a moon-like scenery, the white rocks on the mountaintop and the emerald green water of Lake Yugama feel otherworldly. Yugama is also known to be one of the most acidic lakes in the world.
What's it like bathing in Kusatsu?
The heart and soul of Kusatsu
In the center of Kusatsu is the main area, Yubatake, which translates to English as “hot water field.” A source of hot spring waters for nearby hotels, Yubatake is a unique place where you can observe the sulphuric waters actually flowing down from Mount Shirane.
The active volcano (which last erupted in 2018, after more than 30 years of inactivity) gives the water an extremely hot temperature of about 70 degrees Celsius. It’s impossible to take a bath at that temperature!
That’s why the locals of Kusatsu have developed a technique called yumomi. This describes the process of stirring bathwater using wide wooden planks in order to cool it down instead of adding cold water which would compromise its purity. You can observe this local tradition at Netsu-no-yu, a local onsen next to Yubatake.
Around Yubatake, you can also dip your toes in the public foot baths. Mingle with other tourists and locals as you soak your feet in the soothing hot water.
The best time to admire Yubatake onsen is during the evening. Once the sun sets, multicolored lights around the hot spring turn the scenery into something magical.