Follow the narrow mountain road all the way up from Itaya in Yonezawa, then carry your luggage up a short slope on foot, and you will finally see a single inn hidden at the bottom of a rock-walled valley: this is Ubayu Onsen in Yonezawa, Yamagata Prefecture.
Ubayu Onsen lies in a deep valley on the north side of the Azuma mountain range at an altitude of about 1,300 metres, surrounded on three sides by dramatic reddish-brown and grey rock cliffs, with milky-white, bluish open-air baths right at the foot of the rock walls.
In autumn, beech, Erman’s birch and rowan dye the whole valley yellow, orange and red, and looking up at the autumn leaves from an open-air bath is a classic scene for lovers of Tohoku’s hidden hot springs.
The questions people ask most when planning are: when are the autumn leaves at Ubayu Onsen at their best? Which months is the inn open? Can you still get there after the roads close for winter? Can you just go for a bath without staying overnight? And is the mountain road easy to drive?
This article draws on information published by the Japan Weather Association’s tenki.jp, the Ubayu Onsen Masugataya inn and Yonezawa City to explain the viewing season, opening period, bathing rules, access and itineraries all in one place.
The autumn leaves at Ubayu come much earlier than in the lowlands and the inn is open for only part of the year, so if you get the dates wrong you may make the trip for nothing; we suggest checking the key dates below before you book your trip.
Where Is Ubayu Onsen? Getting to Know the Single Inn Deep in the Azuma Mountains
The address of Ubayu Onsen is 1 Osawa Ubayu, Yonezawa, Yamagata Prefecture, and the whole hot spring has only one inn, Masugataya, making it a classic single-inn hidden hot spring.
Ubayu Onsen Masugataya describes the inn as lying in a valley on the north side of the Azuma range at an altitude of 1,300 metres, backed by primeval forest of Northern Japanese hemlock, beech and Erman’s birch, where Japanese serows are occasionally seen.
The scenery at Ubayu is said to be the finest of any hot spring in Yamagata Prefecture, with the fresh greenery of spring and the autumn leaves particularly highly praised.
There are six spots where hot spring water gushes from the rock walls; Masugataya uses only one of them, and the rest flows straight into the valley stream.
A History Dating Back to 1533 and the Legend of the Mountain Hag
According to Masugataya’s history of Ubayu Onsen, the spring was discovered and opened in 1533 (Tenbun 2) by Endo Ouchikura of Oaza Osawa, who then founded Masugataya, and the current owner is the seventeenth generation.
Legend has it that the founder was originally a mining prospector who roamed the mountains looking for ore veins, and one day in an open-air hot spring he saw a fearsome-looking yamanba (mountain hag) holding a baby.
The yamanba urged him to give up prospecting and become the keeper of this hot spring instead, then vanished together with the baby, and so the place was named “Ubayu” (the hag’s hot spring).
The Three Famous Hot Springs of Mt Azuma in Yonezawa
An old text kept by the inn, the “Unbasenki”, says that the most famous hot springs of Mt Azuma in Yonezawa are Namegawa, Goshiki and Ubayu, and that of the three, Ubayu has the deepest mountains and the most extraordinary scenery.
The text also says that in ancient times the place was cold and treacherous and could only be approached around the sixth and seventh months, showing that Ubayu has always been a hard-to-reach hidden retreat.
Although there is now a road you can drive to nearby, the “hidden hot spring” atmosphere and the difficulty of access remain Ubayu’s defining features to this day.
When Are the Autumn Leaves at Ubayu Onsen at Their Best? Timing Your Visit in 2026 and Next Year
Ubayu Onsen is at a high altitude, and its autumn leaves come much earlier than in central Yonezawa below, which is the first thing you need to know when planning.
The Japan Weather Association’s tenki.jp autumn-leaf page for Namegawa and Ubayu gives the usual peak as mid-September to mid-October, with beech, Erman’s birch and rowan as the autumn-leaf trees.
The 2026 forecast peak field on the same page shows no dates, so we go by the usual peak here and recommend planning your Ubayu visit for late September to early October.
This period falls in the middle of the usual peak, so even if the season runs a little early or late that year, you are less likely to miss it entirely.
The Japan Weather Association’s 2026 Forecast
The autumn-leaf peak forecast published by the Japan Weather Association on 1 October 2026 says that temperatures were low in the first half of September, and in some of the Tohoku mountains that usually peak between September and early October, the leaves turned earlier than usual.
The same forecast also says that a short cold spell in early October will make the leaves turn earlier in parts of Tohoku, mainly in the mountains, but with temperatures higher than average until November, the peak in some places in southern Tohoku will actually be later than usual.
Ubayu is in the mountains of southern Tohoku, so either could happen; the Japan Weather Association plans to update the forecast on tenki.jp three or four times in total up to November, so check the latest conditions again before you set off.
Is It Too Late to Plan Now?
Masugataya’s 2026 season runs until 5 November, and if you go after mid-October, what you see will mostly be the last of the late-autumn leaves and the rock walls after the leaves have fallen.
If you want to see the autumn leaves at their peak, you can plan your trip for late September to early October next year, and book once Masugataya announces the opening period for the new season.
Masugataya began taking bookings for its 2026 season on 1 March 2026; for next year’s opening, go by the inn’s latest announcements.
Opening Period and Winter Road Closures: Dates You Must Check
Ubayu Onsen cannot be visited all year round, and the inn’s opening period and the road’s opening period are two different sets of dates, so it is best to check them separately.
Masugataya’s Opening Period
Masugataya’s announced opening period for the 2026 season is 28 April (Tuesday) to 5 November (Thursday), with a note that it may change because of snowfall and other reasons.
Outside the opening period the inn is closed, so you can neither stay nor take a day bath, and it is not possible to visit in winter.
Winter Road Closure
tenki.jp’s Namegawa and Ubayu page gives the open period as early April to late November 2026, and notes that the road is closed in winter.
The road is open longer than the inn, but an open road does not mean the inn is open, and if you go after early November, even if you can drive up, there will be no hot spring to bathe in.
City Road Closure Announced by Yonezawa City
Yonezawa City’s traffic restriction information lists a section of the Seirokudaira-Goshiki-Ubayu city road between Oaza Itaya and Oaza Osawa that has been temporarily fully closed since 10 November 2025 because the road is narrow.
It is not clear from the map in the notice whether this closed section overlaps with the driving route recommended by Masugataya, so be sure to check with Masugataya which route is currently usable before you set off.
Mountain roads may also be closed at short notice because of rockfalls or heavy rain, so it is safest to check Yonezawa City’s notices again the day before you go.
Must-See Autumn-Leaf Spots: The Open-Air Baths, the Valley Rock Walls and Yakushimori
The autumn leaves at Ubayu Onsen are not a set of viewpoints linked by trails but the whole valley itself, and the area around the inn is the best place to see them.
Autumn Leaves from the Open-Air Baths
tenki.jp describes the view of the autumn leaves from the rock-built open-air baths as being as beautiful as a painting, and this is the reason most people make the special trip to Ubayu.
The open-air baths are in the valley right by the inn, surrounded by towering rock peaks; looking up, you see the autumn leaves on the rock walls and the sky, and you hear the sound of the stream and birdsong.
There are two kinds of open-air bath, mixed and women-only, with rotating time slots, so check the time notices on site before bathing.
The Valley Rock Walls and Primeval Forest
On the way from the car park to the inn, you can see rock walls of reddish-brown and grey, and in autumn the trees in the rock crevices and on the slopes change colour, creating a striking contrast with the colour of the rock.
The walk is not long, but there is an uphill stretch of about 100 metres in front of the inn, so wear comfortable shoes and stop now and then to take in the colours of the valley.
For the Energetic: Climbing Yakushimori
Masugataya’s access and surroundings page says that the 1,538-metre summit of Yakushimori can be reached in about 45 minutes from Ubayu, and that the trail is well maintained, so even beginners can try it.
The summit has a 180-degree view taking in the ridgelines of Mt Takakura and Mt Azuma, and in autumn you can see the leaves turn even earlier than further down.
Work out your return time before you climb, as it gets dark early in the mountains, and bring rain gear, warm clothing and bear deterrents.
Day Bathing, the Hot Spring and Fees
You can also go for a bath in the daytime without staying overnight, but the rules are stricter than at ordinary hot spring facilities, so read them carefully before you go.
Masugataya’s day-visit bathing page states that day bathers are admitted from 9:30 to 15:30, may use only the open-air baths, and will be turned away outside those hours.
There are no fixed closing days for day bathing, the inn does not serve lunch-only visits, the lounge is not open to day visitors, and the only places to rest are the benches in front of the entrance and in the entrance hall.
| Item | Details (as of October 2026) |
|---|---|
| Location | Ubayu Onsen Masugataya, 1 Osawa Ubayu, Yonezawa, Yamagata Prefecture |
| Autumn-leaf season | tenki.jp usual: mid-September to mid-October; recommended: late September to early October |
| 2026 opening period | 28 April to 5 November (may change because of snowfall) |
| Day bathing admission | 9:30 to 15:30, open-air baths only, irregular closures |
| Day bathing fee | Adults 700 yen, children 300 yen (age 3 to primary school) |
| Spring type | Simple acidic sulphur spring, source temperature 51 degrees, free-flowing from the source |
| Parking | Free car park for the inn, about 250 metres on foot to the inn |
| Payment | Credit cards not accepted |
The inn does not accept credit cards, so bring cash for bathing fees, accommodation and souvenirs.
The Hot Spring at Ubayu
Masugataya’s hot spring page lists the water as a simple acidic sulphur spring with a source temperature of 51 degrees and a flow of 300 litres per minute, used free-flowing straight from the source with no water added and no reheating.
The open-air baths are on the hot side, so get in slowly, get out and rest if you feel dizzy, and remember to drink plenty of water.
Overnight guests can use the open-air baths until 10 pm, as well as the separate men’s and women’s indoor hinoki-wood baths, which are open 24 hours.
Stay Overnight or Day Trip?
Day bathers are admitted only until 15:30, and the round trip from Yonezawa or Fukushima is not short, so time can easily get squeezed.
If you want to take your time bathing and viewing the leaves in the early morning or evening when it is quiet, staying a night makes things much more relaxed; Masugataya treats the October and November autumn-leaf season as special dates for stays, so book as early as possible if you want to stay.
You can book a stay at Masugataya by phone or online through the website of the Japan Association for the Protection of Secret Hot Springs (Nihon Hito o Mamoru Kai), and online bookings are accepted 24 hours a day.
Tips for Bathing at a Hidden Hot Spring
Temperatures in the mountains are much lower than in central Yonezawa, and it can be cold even in September, so put on warm clothing straight after your bath.
Ubayu is a sulphurous hot spring, so silver and other metal jewellery can easily discolour; we suggest taking it off and putting it away before bathing.
Follow the rules on site at the mixed open-air bath, and when taking photos of the autumn leaves, avoid getting other bathers in the shot.
The area around the inn is primeval forest and valley, so take all your rubbish back down the mountain with you, and do not leave the paths to go into the valley or onto the rock walls.
Getting to Ubayu Onsen: Train Plus Inn Shuttle, or Driving the Mountain Road
There is no route bus to Ubayu Onsen, and there are only two ways to get there: overnight guests can take JR to Toge Station and then the inn’s shuttle, or you can drive up yourself.
By Train: Toge Station on the JR Ou Main Line and the Inn Shuttle
By train, first take the Tohoku Shinkansen to Fukushima Station, then change to the JR Ou Main Line and get off at Toge Station.
Masugataya runs a shuttle from Toge Station, which takes about 25 minutes to the inn’s car park, followed by a walk of about 200 metres to the inn, of which the last 100 metres or so in front of the inn are uphill.
The shuttle is for overnight guests only, must be booked, and serves only guests arriving by train; it also cannot meet every train, so confirm the train when you book.
Walking from Toge Station to the inn is about 8 kilometres and takes about 2 hours 20 minutes; the mountain road is long and steep, so it is not recommended for ordinary travellers carrying luggage.
By Car: Fukushima-Iizaka IC via National Route 13 to Itaya
The driving route recommended by Masugataya is to leave the Tohoku Expressway at Fukushima-Iizaka IC, follow National Route 13 towards Yonezawa for about 20 minutes, then take the mountain road of about 14 kilometres from Itaya in Yonezawa, which takes about 40 minutes.
tenki.jp, on the other hand, lists Fukushima-Ozaso IC on the Tohoku-Chuo Expressway as the nearest interchange, so you can choose according to where you are coming from.
The final stretch of mountain road is narrow and steep, and drivers need to give way to each other when passing, so if you are not used to Japanese mountain roads, allow plenty of time and drive slowly.
After parking, you still have to walk about 250 metres to the inn, and the last 100 metres or so in front of the inn are uphill, so pulling a large suitcase will be hard work.
Satnav and Mobile Signal
Masugataya warns that setting your satnav by name or facility name can send some models the wrong way, so use the inn’s address instead.
If you enter the phone number of the Masugataya information office, the satnav will take you to the office, about 30 kilometres from the inn, which is a particularly easy mistake to make.
Many places in the mountains have no mobile signal, so if you need to contact the inn, call before you head up; Masugataya has also announced that au mobile phones have had signal there since 13 June 2019.
Private Transfers
The inn shuttle is for overnight guests only, so day bathers basically have to drive themselves, and the final stretch of mountain road is exactly the most nerve-racking part.
If you are travelling with older relatives or children or have a lot of luggage, arranging a transfer from Fukushima Station or Yonezawa Station lets you save your energy for bathing and the autumn leaves.
Suggested Time and Itineraries
If you only take a day bath, including the walk to and from the car park, you will spend about 1 to 2 hours at Ubayu, but you need to add at least half a day for the round trip from Yonezawa or Fukushima.
If you want to climb Yakushimori or take your time viewing the autumn leaves from the open-air baths, it is best to stay a night and give your time to the valley itself.
| Time | Plan | Notes |
|---|---|---|
| Morning | Leave Fukushima Station or Yonezawa Station and head to Itaya via National Route 13 | Check road and inn opening status before setting off |
| Late morning | About 40 minutes on the mountain road to the car park, then walk to the inn | The last 100 metres or so are uphill |
| Midday to afternoon | Bathe in the open-air baths and view the leaves in the valley | Day bathing admission until 15:30 |
| Afternoon | Overnight guests can climb Yakushimori, about 45 minutes to the summit | Keep an eye on sunset time |
| Evening | Day visitors head down before dark; overnight guests relax at the inn | Mountain roads are hard to drive after dark |
If you stay overnight, the next morning you can take another dip in the open-air bath before the day visitors arrive, and watch the autumn leaves as the morning light reaches into the valley.
Allow time for the mountain road on the way down too; we suggest leaving around midday and keeping the afternoon for lunch in central Yonezawa, a stroll around Uesugi Shrine or the journey home.
The Azuma mountain area of Yonezawa also has Tengendai Kogen and Shirabu Onsen, which you can combine with Ubayu on the same autumn trip to Yonezawa.
For the Tengendai Kogen ropeway and autumn-leaf timing, see our Tengendai Kogen Autumn Leaves Guide.
If you are coming or going via Fukushima, you can also stop off around Tsuchiyu Onsen in Fukushima City; see the plans in our Tsuchiyu Onsen Autumn Leaves Guide.
Ubayu Onsen Autumn Leaves FAQ
Q1: When are the autumn leaves at Ubayu Onsen at their best?
tenki.jp gives the usual peak as mid-September to mid-October, and we recommend going between late September and early October, much earlier than in central Yonezawa below.
The Japan Weather Association forecasts that some places in the Tohoku mountains will turn earlier, while some places in southern Tohoku will be later than usual, so check the latest conditions on tenki.jp again before you set off.
Q2: Can I visit Ubayu Onsen in winter?
No: Masugataya’s 2026 season runs from 28 April to 5 November, and tenki.jp also notes that the road is closed in winter, so it cannot be visited in winter.
Q3: Can I bathe without staying overnight?
Yes: day bathers are admitted from 9:30 to 15:30 and may use only the open-air baths, at 700 yen for adults and 300 yen for children, and cards are not accepted.
Q4: Can I get there without a car?
Overnight guests can book the inn’s shuttle from JR Toge Station, but there is no shuttle for day visitors, who need to drive or arrange a private car.
Q5: Is the mountain road easy to drive?
It is about 14 kilometres up from Itaya, and the final stretch is narrow and steep, with drivers giving way to each other when passing; set your satnav by address, and check with Masugataya before you set off which route is usable.
Q6: Are the open-air baths mixed?
Ubayu has a mixed open-air bath and a women-only open-air bath with rotating time slots, so if you are not comfortable with mixed bathing, check the women-only times first.
Conclusion: An Early Autumn in a Hidden Hot Spring at the Bottom of a Rock-Walled Valley
The appeal of Ubayu Onsen is that it really is remote and hard to reach, and precisely because of that, the quiet you feel looking up at the autumn leaves from the open-air bath beneath the rock walls is especially precious.
Remember three things when planning: the recommended viewing period is late September to early October, Masugataya’s 2026 season ends on 5 November, and day bathing admission is only until 15:30 and cards are not accepted.
With these points sorted and plenty of time allowed for the mountain road, Ubayu can become the most memorable stop on an autumn trip to Yonezawa.
Further Reading
- Tengendai Kogen Autumn Leaves Guide, Yamagata: Peak Season, Ropeway Operating Dates, Shirabu Onsen and Access
- Tsuchiyu Onsen Autumn Leaves Guide, Fukushima: Viewing Season, Menuma and Onuma Hike and Access
- Nakatsugawa Gorge Autumn Leaves Guide, Fukushima: Peak Season, Lake Line Opening Period and Access
- Ginzan Onsen Autumn Leaves Guide: Viewing Season, Shirogane Falls, Night Views and Access
There is no route bus to Ubayu Onsen and the inn shuttle is for overnight guests only, so when you are travelling with older relatives or children, have lots of luggage, or want to link Ubayu and spots around Yonezawa in one day, getting around is often the most demanding part.
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