Hoshino Onsen — photo: 663highland · CC BY 2.5 · Wikimedia Commons
The 3 best onsen near Karuizawa
If you are in Karuizawa and want an onsen, the three to look at are Kirizumi, Hoshino and Kawarayu. Of the 11 onsen in our data within 25 km of Karuizawa Station, they are the three best known that you can reach without a car. They are not equally easy from Karuizawa itself. Hoshino is a short bus ride from the station, Kirizumi is a single inn up a valley on the Gunma side of the Usui Pass, and Kawarayu is closer on the map than it is by public transport. Kusatsu, the famous one, is just outside the 25 km line; more on it below.
Why these three, in one paragraph
We did not pick by taste. We took every onsen in our data within 25 km of Karuizawa Station in a straight line, kept the ones that our travel data says you can reach without a car, and ranked them by how often each place's Wikipedia article is read, as a measure of how established it is. The full method, with numbers, is at the end.
A word about the hotel baths
Karuizawa itself is a summer resort, not an old onsen town, and many of its hotels have their own hot spring baths. Our data is organised by hot spring town, not by building, and none of those hotel baths is listed in it as a town of its own, so this guide does not rank them. If you are staying in one, you may not need to go anywhere. This page is for when you want to go out to a bath.
1. Kirizumi: one inn at the end of a valley
Why it made it. Kirizumi Onsen is the best known of the car-free onsen in the 25 km circle, at 551 in our count, just ahead of Hoshino.
The place. A single inn deep in the forest on the Gunma side of the Usui Pass, in Annaka. It is 7.7 km from Karuizawa Station in a straight line, but there is a mountain ridge in between, so you do not get there from the Karuizawa side. Our data records about 8,000 bathers a year. Many Japanese readers know the name from a poem by Saijō Yaso about a hat lost on the road to Kirizumi, which a well-known 1970s film and novel later used.
The water. Recorded at 38.9 °C and pH 7.6, mildly alkaline, and listed as chloride and sulfate. A couple of degrees above body temperature, it makes for a long, lukewarm soak rather than a hot one. The sources put out about 300 litres a minute.
Getting there. Our travel data has you take the JR train to 横川 (Yokokawa Station), the end of the Shin'etsu Line from Takasaki, and ask the inn to collect you; booking sites put the drive at about 30 minutes. From Karuizawa, the JR bus over the Usui Pass runs down to Yokokawa in about 35 minutes. The road ends at a car park below the inn and the last stretch is by the inn's car. The JR Pass covers the train to Yokokawa.
Day bath or overnight. The inn, Kintokan (金湯館), also takes day bathers, but only in a late-morning-to-afternoon window and not on every day; listings give different closing times. Telephone ahead, and if you have no car, ask whether the Yokokawa pick-up runs for day visitors, which is the hard part. Listings describe an indoor bath and no open-air bath. Gunma's tourism site dates the wooden inn building to 1883.
Nearby on foot. 鼻曲山 (Mount Hanamagari), on the ridge between Gunma and Nagano, is 2.2 km from the inn in a straight line, and a trail climbs to it from the Kirizumi side. It is a proper mountain walk; take a hiking map and check the route before you set off.
Good for: a night somewhere with no town at all around it, long lukewarm baths. Watch out for: without a car, even a day bath means arranging the pick-up with the inn. Staying the night is the simpler way to do it.
2. Hoshino: the easy one from Karuizawa
Why it made it. Hoshino Onsen is second at 516. It is also the closest of the three, 4.7 km from Karuizawa Station.
The place. A hot spring in the woods of Naka-Karuizawa, west of the main town. Our data counts 2 inns. Most visitors come for the public day bath, トンボの湯 (Tonbo-no-yu), a few minutes' walk from the Harunire Terrace shops and cafés. The Sezon Museum of Modern Art is 1.1 km away and Shiraito Falls 5.3 km.
The water. Recorded at 46.6 °C and pH 7.4, close to neutral, and listed as chloride and bicarbonate: slightly salty and smooth. It is hotter than Kirizumi and cooler than Kawarayu.
Getting there. From the north exit of Karuizawa Station, the local bus to 星野温泉トンボの湯 takes about 20 minutes. Our travel data has you take the Shinano Railway one stop to 中軽井沢 (Naka-Karuizawa Station) and go on from there; the same buses stop at Naka-Karuizawa. Shinano Railway is not a JR line, so the JR Pass does not cover it. Our data puts it at about 2 hours from Tokyo.
Good for: a bath on a day in Karuizawa, no planning needed, an afternoon combined with the shops and the museum. Watch out for: busy at weekends and in summer, when Karuizawa is full. Check the day bath's hours and price before you go; they change by season.
3. Kawarayu: hot water, a moved town
Why it made it. Kawarayu Onsen is third at 399. Its water is recorded at 79.3 °C, the hottest of the 11 in the circle. Of the 1,167 onsen in our data with a temperature on record, 79 reach that.
The place. An old onsen town in the Agatsuma valley in Gunma. When the Yamba Dam was built, the valley floor was flooded and the town was rebuilt higher up the hillside, so the inns, the public bath 王湯 (Ōyu) and the streets are new, while the spring is old. Our data counts 6 inns. The town is known for a hot water throwing festival on 20 January.
The water. 79.3 °C, listed under three labels: chloride, sulfate and sulfur. Sulfur water can smell of eggs and may tarnish silver, so leave jewellery in your room; our guide to sulfur springs explains the rest. Water this hot is usually cooled before it reaches the bath.
Getting there. The JR Agatsuma Line to 川原湯温泉 (Kawarayu-Onsen Station), then a walk of about 15 minutes uphill. The Agatsuma Line runs from Takasaki, so from Tokyo it is about 2 hours by our data. From Karuizawa, though, it is only 23.5 km in a straight line but there is no direct rail link, and we could not confirm a simple bus route. Treat it as a stop on the Tokyo to Kusatsu side, not a trip from Karuizawa. The JR Pass covers the train.
Good for: the hottest and most mineral water of the three, combining with Kusatsu or Shima on the same side of the mountains. Watch out for: do not plan it as a half-day trip from Karuizawa without a car.
Which of the three?
- An afternoon in Karuizawa, no car: Hoshino.
- The hottest water on record: Kawarayu, 79.3 °C.
- One night, nothing else around: Kirizumi.
- On the way to Kusatsu from Tokyo: Kawarayu.
The places that only just missed
Shoya Onsen (127) would have been fourth: one inn, reached by local bus from Nakagomi Station on the JR Koumi Line, with chloride and bicarbonate water that leaves the ground at 14 °C and is heated. Nakadana Onsen (37) is a walk of about 20 minutes from Komoro Station, recorded at 38 °C and pH 8.4, below the ruins of Komoro Castle.
Kazawa Onsen (248) is better known than either but has no travel data with us, and Takamine Onsen (57), high on the mountain above Komoro, is about 30 minutes by car or taxi from Sakudaira Station.
And Kusatsu? Kusatsu Onsen (5,472) is 31.3 km from Karuizawa Station in a straight line, outside our circle, but it is the one many people mean. A direct bus runs from Karuizawa Station; inns in Kusatsu give the ride as about 70 to 80 minutes. See our Kusatsu guide and the best onsen towns in Gunma.
How we picked these three
- Starting pool: every onsen in our data within 25 km of Karuizawa Station in a straight line: 11 in all, 7 in Nagano and 4 in Gunma.
- No car needed: 7 of the 11 are marked in our travel data as reached without a car: Kirizumi, Hoshino, Kawarayu, Shoya, Nakadana, Asashina and Tengu. Takamine is reached by taxi, and Kazawa, Fuse and Okutsumagoi have no travel data. We kept the 7.
- Known: we ranked the 7 by how often each place's Wikipedia article is read. Kirizumi 551, Hoshino 516, Kawarayu 399, then Shoya 127, Nakadana 37, Asashina 22 and Tengu 17.
- Not used: views, inn quality, price, tattoo policy, food or private baths. We have no data that ranks those fairly, so we did not pretend to.
- About "no car": our travel data is worked out from Tokyo. All three are reachable by train, but only Hoshino is easy from Karuizawa itself; we say so for each.
- About the water: 10 of the 11 have a temperature on record, from Tengu at 9 °C to Kawarayu at 79.3 °C. The water did not decide the ranking.
- Distances are in a straight line from Karuizawa Station; travel times are rough estimates, not a timetable. Check the current route before you go.
Coming from Tokyo? See the best onsen near Tokyo, and for every onsen you can reach by train, onsen on the JR Pass and onsen you can reach without a car. What do "chloride" and "sulfate" mean? See onsen water types. New to this? Start with how an onsen stay actually works and onsen etiquette. Tattooed? Read going to an onsen with tattoos before you book.