Right Onsen › Gunma › Minakami
Mantenboshi no Yu.
4.0★ · 1,450 Google ratings · Minakami, Gunma · まんてん星の湯
✓ Day visitors✓ Outdoor bath✓ Sauna
Before you go
Can you bathe here?
Day visitors
✓ YesStated on the facility's website
Hours
10:00–20:00From the facility's listing
Closed
TuesdaysStated on the facility's website
Last entry
19:00Stated on the facility's website
Tattoos
✕ Not allowedStated on the facility's website
Price
¥950 adultConfirmed by recent visitor reports
Private bath
Yes, by reservationStated on the facility's website
Time limit
3, 5 hours, or full dayReported by two visitors
How we know this
- Day visitors: Multiple reviews confirm day-use bathing is accepted, with pricing varying by duration (3, 5 hours, or full day). · stated on the facility's website, read 2026-09 · 2 visitors, Feb 2026 – Jun 2026
- Closed: stated on the facility's website, read 2026-09
- Last entry: stated on the facility's website, read 2026-09
- Tattoos: stated on the facility's website, read 2026-09
- Price: Advertised price 950 yen for 3 hours (out-of-town adults) as of 2026-07; earlier same price noted 2026-06. · 3 visitors, May 2026 – Jul 2026
- Private bath: stated on the facility's website, read 2026-09
- Time limit: Pricing tiers: 3 hours, 5 hours, and full day; guests must depart at end of selected period. · 2 visitors, May 2026 – Jul 2026
Atmosphere
The bath
What you’ll find
Day-use hot spring with lake views, sauna, and outdoor baths near Sarugakyo, Minakami. Water temperature is very hot.
Bath setup
Indoor baths
2.0Reported by one visitor
Outdoor bath
✓ YesConfirmed by recent visitor reports
Sauna
✓ YesConfirmed by recent visitor reports
Cold bath
✓ YesCold bath present; temperature varies seasonally: warm in summer (above 20°C), near 15°C in winter.Reported by two visitors
Private bath
Yes, by reservationStated on the facility's website
Family bath
✓ YesStated on the facility's website
Spring water
Spring type
sodium-calcium sulfateReported by two visitors
Source temperature
58°CReported by two visitors
Bath temperature
43°CVisitors consistently report main baths around 43°C or hotter; perceived as very hot, difficult for prolonged soaking.Reported by two visitors
Free-flowing (kakenagashi)
Partly confirmedFresh spring water flows continuously through the bath
How we know this
- Indoor baths: Two distinct indoor baths: one pure spring-fed, one blended (warm bath for those seeking lower temperature). · 1 visitor, Feb 2026
- Outdoor bath: Multiple reviews describe outdoor baths with lake views of Akaya Lake; two types named and . · 3 visitors, Jul 2026 – Aug 2026
- Sauna: Facility has a Bona sauna (Finnish-style with specific design); indoor temperature approximately 86°C, not extremely hot. · 4 visitors, Feb 2026 – Aug 2026
- Cold bath: Cold bath present; temperature varies seasonally: warm in summer (above 20°C), near 15°C in winter. · 2 visitors, Jun 2026 – Aug 2026
- Private bath: stated on the facility's website, read 2026-09
- Family bath: Private room rental available with separate charge, valid 3 hours; outdoor baths have dividers for family groupings. · stated on the facility's website, read 2026-09 · 2 visitors, Feb 2026 – May 2026
- Spring type: Posted water analysis lists calcium-sodium-sulfate (sulfate) spring type; faint sulfur odor noted by visitors. · 2 visitors, May 2026 – Jun 2026
- Source temperature: Spring source temperature is 58°C. · 2 visitors, Jun 2026 – Aug 2026
- Bath temperature: Visitors consistently report main baths around 43°C or hotter; perceived as very hot, difficult for prolonged soaking. · 2 visitors, Jun 2026 – Jul 2026
- Free-flowing (kakenagashi): One indoor bath is pure spring-fed at 58°C source temperature; a second indoor bath blends source water with filtered water (warm bath). · 3 visitors, Feb 2026 – Aug 2026
Practical
What you need
Hair dryer
✓ YesHigh-quality Dyson hair dryers available; charged 100 yen for 5 minutes (became fee after around July 2025).Confirmed by recent visitor reports
Accessibility
Step-free entrance and accessible parkingFrom the facility's listing. Bath access not confirmed
Facilities
Rest area
✓ YesConfirmed by recent visitor reports
Restaurant
✓ YesConfirmed by recent visitor reports
How we know this
- Hair dryer: High-quality Dyson hair dryers available; charged 100 yen for 5 minutes (became fee after around July 2025). · 3 visitors, Jul 2026
- Rest area: Rest areas exist on first and second floors with seating and tables; carpeted but described as basic/simple rather than formal tatami. · 3 visitors, May 2026 – Jul 2026
- Restaurant: On-site restaurant serves set meals and local specialties; prices noted as high; separate popular theater venue. · 3 visitors, May 2026 – Jul 2026
Timing
When to go
Quietest Wednesday around 10:00. Busiest Saturday around 17:00.
| 8A | 9A | 10A | 11A | 12P | 13P | 14P | 15P | 16P | 17P | 18P | 19P | 20P | |
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Quiet Busy
Based on Google visit patterns, not a forecast.
Weekly hours
| Day | Hours |
|---|---|
| Monday | 10:00–20:00 |
| Tuesday | Closed |
| Wednesday | 10:00–20:00 |
| Thursday | 10:00–20:00 |
| Friday | 10:00–20:00 |
| Saturday | 10:00–21:00 |
| Sunday | 10:00–21:00 |
Closed Tuesdays.
Getting there
How to get there
Nearest station
Kamimoku8.4 km in a straight line; bus or taxi from the station
Address
1150-1 Sarugakyoonsen, Minakami, Tone District, Gunma 379-1403From the facility's listing
Show a driver
まんてん星の湯The name in Japanese, for a taxi or at the counter
Phone
+81278-66-1126Japanese-speaking. For tattoos or private baths a call is the only sure answer
Website
www.mantenboshinoyu.comOfficial, in Japanese
The map loads only when you ask for it and connects your browser to Google.
Nearby
Other baths close by
Sarugakyo Resident Center public bath.(Non-residents of the district are allowed.)
4.4★ · 0.2 km
✓Day useTattoos ?✓Kakenagashi
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Questions
Common questions
Can I visit Mantenboshi no Yu. without staying overnight?
Multiple reviews confirm day-use bathing is accepted, with pricing varying by duration (3, 5 hours, or full day).
How much does Mantenboshi no Yu. cost?
Advertised price 950 yen for 3 hours (out-of-town adults) as of 2026-07; earlier same price noted 2026-06.
Is the water free-flowing spring water?
One indoor bath is pure spring-fed at 58°C source temperature; a second indoor bath blends source water with filtered water (warm bath).
