Fantastic outdoor open air bath. Massive bath! 700yen for entry, buy towels at 7-11 or use hotel towels as they are pricey at the bath. There is a bathroom and changing room in there but no shower, no shampoo, no body wash. Seems like Friday’s are for mixed gender with swimsuits otherwise gender separated on other days. The walk up is beautiful. The yogurt milk at the end tastes delicious!

Friday evening for mixed bath is super recommended! Bring your own small towel and swimsuit so you will not have to pay extra for them. The locker available inside for 100yen and the entrance fee is 700yen. Don’t forget to try the milk yogurt for 210yen

It was an amazing experience, a privilege to experience bathing in the Sai-no-Kawara hot spring. It’s large and surrounded by the sounds of the river. I was lucky to enjoy this huge hot spring by myself for 15mn as it was a very cold and snowy day in a low tourism season. It’s large enough than 20-30 people can bathe at the same time and you still have enough space! The area around the hot spring is amazing too, especially in the snow season!

No shower areas. Just lockers, one small mirror and a huge outdoor bath. You can’t see the women’s bath from the outside. But you could see the men’s if you are walking from the one coin loop bus stop. The waters are hottt! So good though. Great views of nature, excellent relaxation time especially if it’s snowing. ¥600 but if you get the combined ticket (entry to 3 onsens) for ¥1600, let this be your first so you don’t have to wash/dry your hair cause you won’t have a place to do your hair/make up when you’re done. Take the walk back to the central area, you’ll see how beautiful the park is and there’s also a shrine on the way. So good for photos especially when snowing.

Other than the natural landscape, the other main attraction at the park is Sainokawara Rotenburo - an open air hot spring that is gender separated. I was surprised to find there is no washing (shower) facilities here, so you basically remove your clothes and go straight to the rotenburo. I guess the heat would have killed whatever germs and bacteria on your body! Anyways, common sense meant taking the scoop at the rotenburo entrance and splashing some water on your body before entering into the hot springs. This is the biggest natural hot spring rotenburo I've ever tried - highly recommended!

We went there during the evening. Hot water and cold weather. Perfect mix. Going closer to the waterfalls the water is very very hot. Almost burning. Closer to the fence the water is still hot but beareble. The fact that they have the semi-sinked table where you can have half the body in water and half outside really helps a lot. It's a very nice feature. It's a large onsen but it was not very crowded. The price is 800 yen for the entry. The small towel is 360 yen but if you don't want a 'souvenir' to buy, I recommend bringing your own towel. Nice thing is you can pay the entry with credit card as well. Another plus. They close at 8 PM which is not really ok but I guess during the season they have a different schedule. Going there you have to walk thru a very nice park. I really enjoy it.

It cost ¥800 to enter but well worth it. There is no proper shower place just a gallon of water with some small bucket to splash yourself. Bring your own (big & small) towel. Can be purchased but more pricey. Toliets are available. The onsen is very big also the size a basketball court. Surrounded my nature its very peaceful and relaxing in this public bath. Quite a walk up to this public bath but the scenery was beautiful.

Huge outdoor onsen. No shower just a bath and the changing room. 800yen.

Nice open onsen. I dont see it mentioned in other reviews but the path to this onsen from Yubatake (central area, where most hotels/ryokan are) include shrine visits and saikonawara park where there are a few foot baths. The wall to this bath is very enjoyable! The yogurt milk (you can buy from the ticket seller after bathing) was also delicious. I went here at 7 am and there are only 5 to 6 people in the male onsen and the bath is huge!

Highly recommend outdoor onsen, even in heavy snow fall! We arrived around 530pm after sunset and it was -7 degrees celcius out and snowing quite heavily. The walk into the park was well lit and the main areas were all lit so it made for quite a magical walk up. You can also visits the nearby Inari shire for some added luck. The entrance fee is 700yen which I think is very affordable for such a beautiful outdoor onsen. You should bring your towel as they charge 1350yen for a bath towel and 300yen for a small one. Inside the changing room, you can get a locker for your belongings for 100yen. If not the normal pigeonholes for your clothes will suffice. The men’s pool is bigger than the ladies but the ladies pool is still pretty big for an outdoor onsen. There is no wash area to shampoo or soap up so instead you rinse yourself before getting into the pool. It’s not very well lit so be careful when entering the pool as there are many natural landscaping rocks around the area and you might injure yourself.

Lovely outdoor onsen. 600 yen to get in, but bring your own towel, as large towels are 1300+ also the men's side is pretty open to passersby seeing you from the path, so if you're a shy man, it's probably not for you. For those who can get past that, this is a really unique experience in a large, hot pool, definitely worth a visit.

Large out door hot water pool is amazing. Very cheap price. No shower available though. Sainokawara park is also very beautiful. Around 10 mins from Kusatsu onsen town.

Do NOT come here AFTER a hike. There is no soap or shower room. It was my fault for not noticing the sign, but I wasn't expecting it. There is only a bucket to pour water on yourself. That being said the green water is very pretty and relaxing. Recommended for people just sightseeing.

Love this open-air onsen so much . It is really big so make you feel having bath with nature . I came here in late June , can’t imagine the difference in Winter. This onsen cost 700 yen and towel cost 350yen . No washing place so basically just sock in a nice onsen . Highly recommended

It's an outdoor hot spring with blue sky view and fresh air. When you sit in the water too long and feel too hot, you can stand up for the cold breeze. In winter, the onsen is surrounded by snow, and some of the soft snow even falls from the roof, creating an amazing experience. I highly recommend it. There's no place to shower. Bring your own towel to dry yourself.

Super klassische onsen. Keine Dusche. Alles sehr sauber. Für die Schließfächer benötigt man 100 yen Münzen. Einzelticket: 800 Yen Ink. Der drei Onsen in der Stadt: 1959 Yen.

I was disappointed because it has only a big pool and I paid alone in total 2800¥. It's funny that a towel costs double the price of the entry fee. Then the two employees I went to yesterday at about 5 pm weren't particularly kind. They laughed behind some other western tourists after they asked for information. Not so professional, I hope they didn't do the same to me. They were pretty serious when I asked for a ticket and I talked in japanese. I don't think they like much foreigners!

We went in winter and the walk inside was very slippery from the carpark Located inside Sainokawara Park ,the natural open air bath is great with nice view of the surrounding forest No lockers and advisable to bring your own towels After the onsen, treat yourself to a delicious yogurt milk Entrance fee to onsen is 700 yen

It was pleasant enough. I was rather alarmed to learn of the acidity of the water. The most interesting part of the experience was my encounter with an animal I had never seen before on the way up.

It's a beautiful park.... like yellowstone in USA,; even if you don't want to soak in the open bath, it's a beautiful place to walk. So interesting the stones are green from the water:)

One of my absolute favorite onsen experiences so far. I always enjoy the roten-buro (outdoor baths) style more than indoor ones, and this was no exception. It is very spacious and the water temperature was good, though it varies by location and is obviously hotter the closer you are to the source. Being here actually reminded me of the outdoor anime scenes you will find in many popular shows, which added to the fun! The fee for the onsen is 700 yen, which is well worth it given the size in my opinion. A few things to note: there is no shower area available, but a small area to splash yourself with some water before you get in. There are small and medium sized lockers available for 100 yen inside the changing room. Bring your own towel! Kusatsu onsen is also tattoo friendly, so no need to cover up! Obviously no photos allowed in the onsen area. Enjoy!

A pleasant open air Onsen with a mix of locals and tourists. You can purchase a small or large towel if you don’t have one for a small amount of money. Lockers are 100 yen. There are no washing facilities before entering the Onsen which can be a negative for some. For me, as a first time public bather… I didn’t mind not having to sit on a stool naked and soap up first and actually appreciated being able to get straight into the pool. I found the water pleasant and the Onsen not too crowded. A nice option for tourists especially those who are new to the Onsen experience.

Excellent natural outdoor onsen spa. Well worth a visit. Relaxing to be outside in the open air! Very organised. Bring your own towel and it is not expensive.

The bath was large and a good temperature. I went at 5:30pm on a Monday and no one else was there, so I was able to try out various places in the water. There were rock formations and a wooden platform in the middle to sit on. It was very serene with the steam rising off the water at night. The lighting is very low at the entrance and the ground in the pool is uneven so be careful when exiting and entering the pool.

Glorious outdoor onsen. Come here for the refreshing and liberating experience of an onsen in nature. Surrounded by trees and mountains. Basic facilities, with no showers. ¥700 to enter at the time of writing, and towels are all chargeable, so recommend bringing your own. Lockers are ¥100 non-refundable, so make sure you’ve everyone you need before locking.

Really great place! The outdoor baths are amazing. You can also do mixed bathing there. The walk up is also gorgeous with the pools and falls of hot water.

It was an impressive open air bath, its very spacious, and the garden that leads up to the hotspring is really beautiful as well! Highly recommended. However, please keep in mind that there are no showers provided, and it becomes a mixed gender bath every friday evening.

It was a great experience to have an public Open -air Japanese onsen, most of the other onsen are indoor lacking of connection to the natural nature of onsen. The small jogging pants from the parking to this onsen have built up the feeling as march into the natural.

Very impressive Onsen bath. Feel relax. Deduct 1 star because there is no shower room.

Great massive open bath. Seperate between women and me. No bathing before hand is needed since theres no place you can wash yourself anyway.

The men's bath is visible to those visiting and walking up the sainokawara park. Nonetheless it's a cheap place to have a great open air onsen experience!! Definitely magical when it's night/snowing. Milk is available at 200 yen.

Super schönes Onsen mitten in der Natur! Das Bad kostet Eintritt (1400yen). Es gibt keine klassische Dusche für die Reinigung davor. Das Frauenbad war super leer und teilweise war ich sogar alleine. Würde immer wiederkommen

Onsen is 10/10, no doubt, especially for the price. Do go in winter, better still during a snowstorm at night. The lockers and changing rooms could use some improvement though. Mind you, no showers or soap inside.