Doai Onsen 度合温泉 is a Ryokan deep in the forests and mountains of northern Nakatsuragawa, close enough to the southern border of Gero to consider it like Hida. Once you reach the turn-off from the main road, it takes over 30 minutes of driving on a narrow single lane road through the forest and along valley cliffs to reach the remote buildings. It's deep enough in the forest that cellphone reception is hard to come by.
The purpose of the inn is to relax with nature while shedding the modern conveniences of the Internet and electricity. To become less digital and more analogue. There are very few lights at Doai Onsen and after 10pm, the generator is turned off. The hallways and rooms are only illuminated by lantern at that point, of which there are more than 300 at the inn in various styles. The numerous amount of lanterns have become the mascot of Doai Onsen, so Doai is also known as the Lamp Inn ランプの宿
I found this place while searching around on Google Maps looking for places to hike and explore, and with my friends Dirk and Zach coming to visit in September, we decided to give it a try and stay a night. They have a very modern website which made it easy to reserve a room and the prices were very good compared to other expensive onsens and ryokans. Only 15000円 (~$100) a night, which includes dinner and breakfast.
After an obnoxious lunch, we arrived around 4pm. There was a bit of confusion on when we were supposed to arrive, but it all worked out. Check-in official began at 3pm, but we could still arive by 5pm. We were sharing the inn with 2 other groups. One group was just a mother and son. The other group was a larger older family of about 6 people.
The inn seemed like the perfect size for our 3 groups. I don't know if any of the rooms had names, but we were given the room nearest to the entrance. There were two connected tatami rooms that were opened up so we had a really large space, a total of 20 tatami mats! The group of 6 had the whole lower wing to themselves, so they probably had probably double the space.
While some others had already arrived, we were able to hop in the baths first and have them to ourselves before the other groups. Dinner was served around 6:15pm (later than usual), so there was a lot of time to soak.
There were separated baths for men and women which alternated in the night and morning. The men had the larger bath in the evening. The baths are kept warm from a wood burning stove underneath, known as the Goemon method. However, heated water from the tap is boiled using electricity from the generator.
There were two baths available. Both were filled with spring water from the mountain. One was full of water that was naturally heated by the thermals of the mountain. The other was from cool spring water that was manually heated. Both contain the natural minerals that onsen in the mountains are known for, such as sodium bicarbonate (baking soda, essentially). These baths repair and soothe rough skin and cuts by eating away at dead skin on the surface.
I love sitting in the warm baths. Natural onsens are my favorite. :) The open window looked out over the gorge with the Tsukechi river below. There were the 3 of us in the bath, so we were talking about things. But, it is always nice to just sit in the bath and listen the wind blow through the leaves and the water flow through the river. There were hot and cold taps for the baths, so I could douse myself with cold water when I felt I was getting too hot.
It was still pretty early out, but it would've been really nice to come back after the sunset and soak in the tub only lit by lantern light. The lanterns keep the insects away, so you could just relax.
We stayed in the baths for about 40 minutes and were leaving just as the next group came in. We goofed around in the room for about an hour until the hostess notified everyone of dinner.
The dinner was incredible. Often when dinner is served at an enkai or ryokan, there is usually not enough (for me) to go around. I'm always leave feeling unsatisfied and that I could've had more. This was not the case at Doai. The meal began with mountain vegetables 山菜, tofu, mochi, and some Iwana sashimi. Iwana is the most common and prevalent fish in the rivers of these moutanins, and local restaurants often serve it.
More and more dishes kept coming out. We had baked Iwana, tempura, and a very large Gohei mochi. Gohei mochi 五平餅 is fried mochi on a stick with a sweet syrup sauce painted on the top. They are usually the size of a popsicle, but this beast was larger than most pancakes. It was so good.
It was an amazing meal with so much delicious food. One of the best meals I've had in a while.
With dinner finished, we had the lamp and safety demonstration at 7:30pm. I thought that this would take only a couple of minutes so I could be back in the onsen bath before they closed, but the lamp demonstration was only the beginning of the night's activities.
Arriving in the common area, we were given a puzzle, a wooden needle threaded in a denim jacket. "Remove the needle from the jacket and get a prize!" It seemed pretty easy and I remember seeing a similar looking puzzle on YouTube a while ago where a person removed a bike lock from a lamp post. That was a different solve, though.
We fumbled around at the puzzle until everyone arrived and began the lamp demonstration. The host explained how to correctly light the lamp by achieving the correct flame size after lighting the wick with a match. The two sides of the flame should create an arch when holding the glass above the flame, creating an image that kinda looks like Batman. If the flame is too intense, there's too much wick. The reverse is true too.
He also mentioned that because the wick is completely soaked in oil, it never burns itself. The wick isn't like the wick of a candle. If the flame dies down, it's because of the oil running low, not because the wick is too low. As such, you should never push too much of the wick out of the base. In the short term, you might get the light you want, but after an hour there will be a massive flame burning out of the lantern. ALWAYS make sure the initial lighting creates the batman shape, and the lantern will be fine for the whole night.
Also, when you want to extinguish the flame, don't mess with the wick. Simply blow over the top of the glass and the air circulation will put out the light.
We were each given our own lantern to light the correct way. The wicks were already in the best position, so we didn't have to mess with it. After striking our match and lighting the wick, we just observed the flame's shape to verify it was correct.
Then, continuing with lighting lanterns, he had us lighting the lamps using the arcane method of flint and steel, the same way his Japanese ancestors like lanterns. We started off with a standard cut of steel against stones. But, if we couldn't handle it, we could use easier steel which guaranteed sparks. Every strike on the flint should try and knock the sparks into some padded cloth, and then attempt to transfer the spark into the lantern to light it.
It was not so easy. I could not get the right angle or I was holding it too hard. I moved on to the easy steel and sparks were flying immediately. Lighting the lantern was so much easier using the "starter" steel. Zach and Dirk were much better at using the true steel method.
Moving on from the lantern, there were many more activities. We continued with the wooden thread puzzle, and he continued to give us more and more hints until we understood how to solve it. Upon solving it, we could keep the wooden needle and as a prize, we were given an extra one to give to a friend. (Here's how to solve it) The host gave us some construction paper with lines to cut out and create a skeleton figure. He also taught us some ways of tying knots using rope, which could help us repel down a cliff or carrying something up. He gave us more prints of the cutouts and rope instructions.
The night kept moving with all the activities that it was nearly 10pm. The host said there were more games in the morning, and you can win a prize if you remember how to tie the ropes. But with the generator going off in about 10 minutes, we all retired to our rooms for the night. Each group could take a lantern back to the room to use after lights out.
With the generator off, the lanterns were dim, but being out in the pitch darkness of the forest boosted their glow considerably. The hallways filled with the warm light. Although, if we had to use the bathroom, we just used the light on our phones.
If I was alone, I would have loved to fall asleep to the wind in the trees and the water in the river. But, I put in my earphones to guarantee that I could actually sleep through the night without waking from the smallest of sounds.
The morning came and the light filled our room. It was around 6:30, I think? I heard some odd pinking sound, which I thought was water drops tinking into a thin metal gutter. It was not.
Some of the other family members were in the common area with the host's BB rifle shooting at a tin target in the forest. I went to join them and shot a few rounds. If you called your shot and hit the target within 2 tries, you won a prize, a compact flint and steel set with some cloth to catch the spark.
The baths were open at 7am, so I went back to the room to gather my things for the bath.
We were on the left side now. It was the same layout, except the baths were slightly smaller. It was totally fine though. You don't want to stay in the bath for very long in the morning, otherwise you'll waste all your strength for the day. I think I spent about 15 minutes in the water as others came and went.
Back in the common area, more of us gathered to shoot airguns and play with the wooden games he had laid out. Those host asked us if we remembered the knot tying from the previous night. By performing the knot successfully, the prize was a bear bell to use in the forest when hiking.
At 8 o'clock, our breakfast was served. More mountain vegetables, Iwana, Miso soup, and other staples of a Japanese breakfast. Plenty of rice, too.
After breakfast, we continued shooting guns and playing games in the common area and were given our bill for our stay. It was 45900円 divided between the 3 of us. 15300円 for one person, which included an amazing dinner, a delicious breakfast, an onsen towel, portable flint/steel, the wooden needle puzzle, a bear bell, and a soak in their onsen is a damn steal.
It was an incredible stay at a beautiful place that I will forever compare with all my subsequent ryokan stays. I think it would be even better paired with hiking in the area prior to staying the night. After we left, we visited the waterfall just down the road, and also visited the Tsukechi gorge which wasn't too far away.
You can see more information on the Doai Onsen website. I also scanned their brochure which has some more information. You may notice on their brochure that they have increased prices in the past. Their website currently says that they plan on increasing prices again next year in 2026, but the experience is well worth it.
