Right Onsen › Gunma › Shimonita
Yachiyo Onsen Seri-no-Yu
4.2★ · 552 Google ratings · Shimonita, Gunma · 八千代温泉 芹の湯
✓ Natural hot-spring water✓ Free-flowing source water✓ Rest area✓ Restaurant
Before you go
Can you bathe here?
Day visitors
✓ YesThe inn used to offer lodging but is now day-use only.stated by 2 visitors · May 2026
Hours
11:00–20:00 · closed Thursdayfrom the facility listing
Price
¥800Current adult admission is consistently 800 yen (it was 500 yen in 2022 and 700 yen in 2023 per one long-time reviewer's history).stated by 5 visitors · Jan 2026 – Aug 2026
Bathing arrangement
Men and women separateMen's and women's baths are separate but swap rooms daily.stated by 3 visitors · Jan 2026 – May 2026
Tattoos
Not known · call aheadno policy stated in the 36 recent reviews we read or on the facility's website
Watch out
Payment
Payment is cash only.
stated by 2 visitors · Jan 2026The bath
What you’ll find
A remote, rustic day-only hidden-gem bathhouse in Shimonita with a strongly saline, slippery carbonated chloride-bicarbonate spring, indoor-only tubs that swap gender daily, a beloved shop dog, and a restaurant, but no rest area and one detailed review reporting real ventilation/oxygen problems in the sealed bathroom.
Outdoor bath
NoBaths are indoor only, no outdoor bath and no sauna.stated by 2 visitors · Jan 2026 – Jun 2026
Indoor baths
2Two indoor tubs (a stone one and a cypress-wood one) that swap between men's and women's use daily.stated by 2 visitors · Jan 2026
Sauna
NoNo sauna on site.stated by 1 visitor · Jun 2026
Rest area
NoThere is no dedicated rest area outside of chairs by the bath entrance or the dining room (which is only accessible when ordering food).stated by 2 visitors · Apr 2026
Restaurant
✓ YesA well-regarded restaurant (known for grilled offal/motsu and udon) operates alongside the bath.stated by 6 visitors · Jan 2026 – Aug 2026
Lodging
NoSignage suggests it once offered lodging ('mountain inn'), but reviewers confirm it no longer does.stated by 2 visitors · May 2026
The water
Free-flowing (kakenagashi)
PartlyWidely called source-fed kakenagashi by casual visitors, but one very detailed technical review notes no visible overflow and suspects the water is actually heated and possibly diluted rather than true kakenagashi.stated by 5 visitors · May 2025 – Aug 2026
Spring type
Sodium chloride-bicarbonate cold mineral spring (carbonated)Officially classified as a carbonated sodium chloride-bicarbonate cold spring; widely described by other reviewers simply as strongly salty and slick.stated by 2 visitors · Jan 2026 – May 2026
Source temperature
13.8°COne long-time reviewer records source temperature as 13.8C on one visit and 10.8C on another, consistent with a cold mineral spring that must be heated.stated by 2 visitors · Jan 2026 – May 2026
pH
pH 6.3The spring's pH is measured at 6.3, in the mid-6 range.stated by 2 visitors · Jan 2026
Heated
✓ YesThe cold source spring is heated before entering the tubs; one reviewer suspects added water too, though another explicitly says no water is added.stated by 3 visitors · Jan 2026 – May 2026
Practical
What to bring
Payment
Cash onlyPayment is cash only.stated by 2 visitors · Jan 2026
Lockers
✓ FreeFree valuables lockers are provided.stated by 4 visitors · May 2026 – Aug 2026
Hair dryer
✓ YesHair dryers are available in the changing room.stated by 2 visitors · Jan 2026 – Aug 2026
Guide
What visitors add
The water
The water is a strongly salty, notably slippery ('toro-toro'/'nuru-nuru') sodium-chloride/bicarbonate cold mineral spring: one reviewer cites the official classification (CO2-bearing sodium-chloride & bicarbonate cold spring, hypertonic, pH ~6.3); at least eight distinct reviewers describe the salty taste and/or slippery skin feel, and several describe brownish/turbid or faintly yellow color. One reviewer notes strong sweating and one that fingertips got rough an hour after bathing (concentration of salts).
stated by 10 visitors · Jan 2026 – Aug 2026The water
Bath temperature reports conflict and appear to have changed over time: five reviewers describe the water as lukewarm/nuru-yu, but two spring-2026 reviewers found it hot or 'somewhat hot', one regular (May 2026) complains the temperature was recently raised so long soaks are no longer possible, and one (Jan 2026) measured the two tubs at 40°C and 41°C with the spout at about 38°C.
stated by 8 visitors · Jan 2026 – Aug 2026Water handling
The source is a cold mineral spring (reviewer-cited source temperatures 10.8°C and 13.8°C) that is heated for bathing: four reviewers describe it as gensen kakenagashi, one of whom states it is heated but with no added water; two others infer heating from hot water felt rising under the tub floor (one speculating added hot water). One critical reviewer (Jan 2026) says the left/stone bath had low inflow, no overflow over the rim, and floating deposits.
stated by 6 visitors · Jan 2026 – Aug 2026Price
Adult admission is 800 yen — five distinct reviewers (Jan–Aug 2026); one specifies adults from junior-high age 800 yen and elementary-school children 500 yen, and one says using only the restaurant costs 300 yen. One multi-visit reviewer documents the price rising over time: 500 yen in Jan 2022, 700 yen by Nov 2023.
stated by 5 visitors · Jan 2026 – Aug 2026Towels, soap & lockers
Free keyed valuables lockers are available (located in front of the bath entrances): four distinct reviewers confirm free lockers; the changing room itself has only baskets (about 10) plus dryer, fan and sink per two reviewers.
stated by 4 visitors · Jan 2026 – Aug 2026Staffing
There is no reception desk — you pay the owner/staff found in the entrance hall or restaurant: one reviewer describes this setup in detail, another was greeted at the door by the owner who explained lockers and warned of slippery floors. Service impressions conflict: two reviewers praise the staff as very pleasant, while one (Jan 2026) found the owner dismissive when raising the ventilation complaint.
stated by 4 visitors · Jan 2026 – May 2026Timing
When to go
Quietest Friday around 19:00; busiest Sunday around 12:00. Measured by Google over past visits, not a forecast.
| 8A | 9A | 10A | 11A | 12P | 13P | 14P | 15P | 16P | 17P | 18P | 19P | 20P | |
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Quiet Busy
| Day | Hours |
|---|---|
| Monday | 11:00–20:00 |
| Tuesday | 11:00–20:00 |
| Wednesday | 11:00–20:00 |
| Thursday | Closed |
| Friday | 11:00–20:00 |
| Saturday | 11:00–20:00 |
| Sunday | 11:00–20:00 |
Closed Thursday.
Practical
Plan your visit
📍 12809-1 Nishinomaki, Shimonita, Kanra District, Gunma 370-2627
🚃 Yokokawa station, 9.9 km
📞 +81274-84-3812
📋 Show at the counter: 八千代温泉 芹の湯
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