Kusatsu Onsen is not the easiest place to get to from Yokosuka. It took four and a half hours, three trains, and a bus. Was it worth it? Oh, yes.

The town is located 1200 meters above sea level, an elevation high enough that the town is a popular destination for skiiers. Despite the pristine slopes, the undisputed star of the town is the thermal waters.

Kusatsu Onsen happens to be ranked as one of the three best onsen towns in Japan. In a country that takes its onsen and bathing rituals with deadly seriousness, that says a lot. Indeed, during the Edo period the Tokugawa shogunate considered the water’s properties so beneficial that water was transported from Kusatsu to Edo in barrels.

Thanks to Mt. Shirane, an active volcano, the town is gifted with 32,000 liters of natural water per minute.

Pristine Mountain Town

The architecture in Kusatsu Onsen is beautiful and restrained. With a population of only 6,255, the town has been meticulous about maintaining its appeal as an intimate retreat. As such, the color scheme consists of tasteful whites, creams, grays, and wood browns. Even the vending machines and 7-11 convenience store have had their designs modified to blend with the architecture. Despite the fumes coming off the man-made collection pond, it felt like I was in Austria or Germany.

As it turns out, I was not too far off in thinking there was a strong German influence. During the Meiji era, German researcher Dr. Erwin von Bälz ventured to Kusatsu several times to study the anti-bacterial properties.

More recently, the Kusatsu Onsen waters were studied by researchers at Gunma University to determine if they were effective against COVID. Their research indicated that the water’s high alkalinity was indeed good at combatting the virus. As a result, many “hand baths” with hot thermal water were installed throughout town in lieu of hand-sanitation stations.

Alas, there are limitations. By every hand bath are signs in Japanese and English warning visitors not to ingest the water.


The star of the town is Yubatake, literally “hot water field”. The man-made collection pool is THE focal point around which the town is built. I was mesmerized by the color of the 95 degree Celsius (203 degrees Fahrenheit) water. Was it jade? Turquoise? Emerald? The color of the water pools reminded me of precious jewels. It was all the more striking because of the deliberately monochromatic ryokans and restaurants that surrounded it.

Yubatake is lovely to visit during the day when you can appreciate the green hues. If you are in Kusatsu Onsen overnight, you are also in for a treat: the entire area is illuminated with dramatic lighting.

As one can imagine, this is a popular hangout spot for couples, youth, and small groups. Regardless, you can’t come to Kusatsu Onsen at night and NOT take a stroll around Yubatake.

Kusatsu Onsen
The Ladies sing traditional folk songs as they use wooden planks to cool the water.

Cooling the Water – Yomomi Style

For several centuries, servants in most of Europe put considerable effort into heating and carrying kettles of water to fill tubs. Those living at Kusatsu Onsen had the opposite problem: how to cool this fabulous 95 degree Celsius water so that humans could safely enjoy the benefits?

My initial thought was a little too obvious. There was plenty of snow and river water – why not re-direct a nearby stream or shovel in some snow?

Yes, snow and rainwater would cool the temperature. However, it would also dilute the special composition. The town created wooden conduits to vector water into different areas, which brought the temperature down to 50 degrees Celsius (122 degrees Fahrenheit). To further bring the temperature down, the Japanese devised a method by which women used long wooden planks to agitate the water. This technique, known as yomomi, released the heat and preserved the quality.

Fortunately, tourists can observe yomomi at a converted public bath house adjacent to Yubatake. Kusatsu Onsen Netsunoyu hosts multiple daily performances for tourists that combine traditional song and dance with a yomomi demonstration. As one might imagine, tickets (¥700 ($5.20) for adults) are very popular.

Once inside, guests can watch as six women in matching dress sing in unison as they rhythmically shifted the planks back at forth, up and down, visibly releasing the steam.

Bathing in Nature at Sainokawara Park

I was so excited to my first full-body natural public onsen. The day before, I had scouted the location to see if the area was visible from higher ground. Rest assured, Modest Ones, you will be well shielded from prying eyes by discreet wooden fences.

I was especially happy because it had snowed overnight and the sky was still full of delicious juicy snowflakes. I was thrilled. What better conditions to visit Sainokawara Park?

The Sainokawara Park onsen are separated by gender and the rules are slightly different than the onsen I have visited in the past – there were no showers. (At most indoor onsen, you sit on stools and wash yourself before entering the bath, and again on exit.) Here, you simply scoop water from an outdoor basin over yourself before and after you exit the onsen. The entry fee is ¥700.

For guests’ privacy, no photos are allowed inside the changing rooms or in the bath. The locker rooms are exquisitely clean. Thankfully – given that you are naked and it is freezing – it is a mere few feet from the locker room to the hot onsen water. I was blown away by the size and design of the ladies’ onsen. It was enormous – at least 30 meters long. Enormous, thoughtfully placed rocks in the onsen allow the shy to find a bit of privacy, and a waterfall generated so much steam that a woman 20 meters away was practically invisible.

Although I shared the bath with two other females, it felt like I had the entire space to myself. I was surrounded by trees and rocks and crystal clear jade water. Snow fell heavily on my neck and shoulders, but I was not the least bit cold. The temperature was absolutely perfect.

I was utterly and completely happy.

Sainokawara and Walking Paths

There are many people who do not feel comfortable bathing with complete strangers. Not to worry, you can still enjoy the benefits of outdoor bathing WITHOUT removing anything more than socks and shoes. 🙂

Sainokawara is a 10 minute walk from the town center and has several natural pools and streams of varying colors. A few such areas are designated as foot baths and provide the chance to dip your feet in FOR FREE. Generally speaking, the more intense the color of the water, the hotter the temperature. One pool had a sign describing it as the “Devil’s Kettle”. The water was emerald green, and oh yes, it was just short of scalding!

If you would prefer to skip the baths entirely, I still recommend Sainokawara for its lovely wooded walking paths.

Onsen Town

There are plenty of free outdoor foot and hand baths by Yubatake and throughout town. Fancy an indoor soak instead? Many ryokan have in-house baths, and some offer non-guests the ability to drop-in for a small fee (normally ¥500 ($3.71)).

Generally, I enjoy going to ryokan onsen. However, I am worried that I have been spoiled for life by the magical outdoor onsen at Sainokawara. Truthfully, I had not expected to enjoy it as much as I did.

It was so much fun wandering the streets of Kusatsu. As an onsen town, it is not at all improper to wander the streets dressed in traditional yukata (Japanese robes) and sandals, if you so choose. There were actually quite a few braving the snow in yukata and sandals. Alas, I am not quite so courageous.

At one shrine I saw the most beautiful hand-washing station. In an homage to the town’s bathing culture, it was playfully decorated with flowers and yellow bathing ducks.

I used the ladle to wash my hands and had a bit of a shock: during my entire time in Kusatsu, the only cold water I touched came from that shrine basin.

Special Foods to Try

Kutastu has the most awesome maitake (mushroom) tempura. If you are a mushroom lover, the maitake tempura alone is worth a trip. Another super tasty food to try are tomago onsen (soft-boiled eggs) that are heated in the onsen water.

Gunma Prefecture is also renowned for the quality of its beef, and quite a few restaurants feature different beef items on their menus. How good is the food? Good enough that the Japanese line outside select restaurants in rain and snow for some forty minutes.

I do not have the same stamina to wait for a top tier restaurant, and still had a fantastic dining experience. A delicious full lunch and dinner cost approximately ¥1600 ($11.88).

It was a little too cold for me to try wearing the robe outdoors, but come summer I would love to rock a yukata!

If You Go

I went to Kusatsu Onsen during President’s Day weekend and booked a hotel for Sunday night that was less than a five minute walk from Yubatake. It is a favorite trick of mine to try and do the bulk of my exploring on a week day. As a result, I benefited from a favorable hotel rate and low crowds. With people either at work or blissed out from so much happy bathing, the streets were all but empty as I walked through town at 8 a.m.

I love observing life in the hours before a town comes to life. As such, I watched as workers carefully stepped into Yubatake in protective gear to harvest the sulfuric byproduct known as “hot water flowers”, a.k.a. mineral bath salts.

Shops do not open until around 9 a.m., with most restaurants opening for lunch around 11.

Is it possible to make Kusatsu Onsen a day trip from Tokyo or Yokosuka? Yes, but given that a one-way trip takes at least four hours, I highly recommend making it an overnight trip. After all, an onsen town is all about relaxation and contemplating nature. Sitting in the outdoor natural waters with snow hitting my shoulders was an unforgettable experience.

And yes, my skin is super soft from all those lovely minerals. 🙂

If you have the time, I recommend combining Kusatsu with a trip to nearby Takasaki, birthplace of the Daruma Doll.

Here’s wishing you a safe, healthy, and happy adventure!

By Katie Cerezo

Thank you so much for visiting. 😊 I have always loved traveling, and my legs are my primary means of transportation. It's a beautiful world, and I'm eager to explore it…one step at a time.

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