car travel

Numajiri Onsen

After a very early Christmas Party and getting my snow tires changed, I set out from Sanjo on Saturday morning for Fukushima Prefecture. My goal was Numajiri Onsen, a natural hot spring in the mountains. I have been wanting to go ever since I found out about it here. The reason is that unlike most onsen in Japan, you can visit and bathe in the natural, unrefined source of the spring. Usually, when you go to an onsen, you pay an entrance fee into a specific bath that has water piped in from the nearby spring. While this is still a great experience, the source itself is usually inaccessible. So I was pretty jazzed about the chance to visit this place.

I took route 459 from Gosen in Niigata across Honshu to Fukushima, which sits on the eastern half of the island. Rather than spending money on the expressway, I opted for this route which parallels the expressway, but which is craaaaazy narrow and windy. I took me 4 1/2 hours to get from Sanjo in Niigata to Numajiri in Fukushima, arriving at 2 pm where I was to start out for the hike.

Numajiri Ski Area

Normally, you can drive half the hike up a narrow road through the Numajiri Ski Area. But there was a foot of snow on the ground. So I hiked through that too. The weather was cloudy and a bit windy, but I was well prepared with warm gear. An old couple had broken the trail a bit for me with snowshoes, although in some of the drifted areas I sunk in up to my knees in snow. I still made it the 4 km to the spring in about an hour. I had less than two hours of daylight, and it was cold and windy, but I hopped in the hot springs, albeit hesitantly.

Numajiri Valley

The water is milky and the rocks that the water flows over are coated in sulphur residue. The source of the spring is spread over a large valley area, and flows down as a river, with nice little pools for bathing.


The whole spring produces 10,000 liters of hot, acidic water every minute. The pH of the spring is 1.9 – think lemon juice. Luckily I didn’t have any open wounds.


After 30 minutes of bathing, I hopped out, put my clothes on, and set out. It could have been a more relaxing experience. With the encroaching darkness, the dark clouds, the snow, and the creepily spray-painted “GASU KIKEN” (Dangerous Gas!) on a nearby rock, I wasn’t able to completely relax. I think late October would be the perfect time for this trip, preferrably with a hiking partner, earlier in the day. It wouldn’t be as cold, there would be less snow, and you’d see some nice fall colors.

Arriving back at the car, I decided to overnight it and really break in my Subaru, so I slept in the back. It got to about 20 degrees or so that night, and my 20 degree REI sleeping bag did the job. The next morning I headed back to Murakami, taking a very scenic, totally indirect route (several passes were closed for the winter) and hitting two more onsen on the way back.

Pretty Road

4 replies on “Numajiri Onsen”

Hey Sean,

Hot spring looks awesome. Visited one up like it on the Shiretoko peninsula a few years back. It’s closed now I hear due to too many people getting hurt hiking up the slippery riverbed to the pool. The natural ones are the best, but I did recently sample four developed onsen, including three that were new to me.

Sorry we didn’t get to connect at all during my recent visit to Hokkaido. We had a full schedule and I know you had that rehearsal. Hope it went well. Performance was this past weekend?

I really do hope to work over there again some day, so maybe we’ll have another chance. And who knows I may do the exchange again next year — that’d be my sixth time.

By the way, I did see Nik albeit barely. He was sick when I arrived, then well enough for a night of kaiten sushi and the spa at Kamiyubetsu, then he was sick again for the rest of the visit.

Still getting caught up here after the two weeks away, so I better get back to it.

Take care, Paul

Hi Sean,

I am glad that at least 1 person tried the onsen I described on the Secret Japan website! I am also rather impressed that you hiked to the onsen when there was already so much snow. Some parts of the hike are rather dangerous, especially the section next to the waterfall: was is OK with snow on the path?

At least, I guess you did not have too many persons soaking around you 😉

I added a link to this page from our guide, too. Wouldn’t you be interested to contribute to our guides? You seem to like “off the beaten tracks” destinations!

Best regards,


hey Sean! nice report buddy. this place isnt too far from my place here in Fukushima-shi. love it there. but last time we went there was a gate blocking the path from the entrance at the bottom of numajiri ski resort. so after moving that and getting to the top car park we found out why. the walking path was trashed from winter and pretty dangerous in a few parts. then after getting there the water was cold!! ahhgg. lucky it was still warm for you in winter! hit me up if your back this way again and i can show you some other awesome ones around. cheers, Pete

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