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Mantenboshi no Yu.

まんてん星の湯まんてんほしのゆ

Other
Kanto·Gunma

Day Use

Yes
Mon10:00–20:00
TueClosed
Wed10:00–20:00
Thu10:00–20:00
Fri10:00–20:00
Sat10:00–20:00
Sun10:00–20:00

Closed on Tuesdays, except when a Tuesday falls on a public holiday, when it stays open.

¥950

Day tickets are time-based: 3 hours is 950 yen for adults and 700 yen for children, 5 hours is 1,200 yen, a full day is 1,800 yen, and a night ticket is 850 yen, all with the bathing tax included.

Bathing & Water

Natural onsen water

Uses natural hot spring water

Outdoor BathYes

Open-air outdoor bath

Indoor BathYes

Enclosed indoor bathing area

SaunaYes

Dry heat sauna room

Cold BathYes

Cold water plunge bath, typically used after sauna

Capabilities

Private BathYes

Private bath available for day-use visitors or hotel guests to reserve

Mixed BathingNo

Shared bathing area for all genders

House rules restrict mixed bathing to young children with a parent; from elementary-school age, gender-specific baths (男性浴場/女性浴場) are required.

Policies & Services

TattooNo

Allows entry with visible tattoos

A 2025-10 review reports a guest with a full-back tattoo was admitted without issue despite this posted policy; kept the official stated policy as authoritative.

KidsWith Conditions

Welcomes children and families

Children below elementary-school age may bathe with an opposite-gender parent; from elementary age they must use the gender-appropriate bath.

DiningYes

Restaurant or dining open to visitors (not just hotel meal plans)

WashingYes

Shower, wash stations, soap and shampoo provided

TowelsYes

Towels available to rent or borrow

Only sourced from a 2022 review describing a paid towel loan at reception; not confirmed on the official site.

Rest AreaYes

Relaxation space for after bathing

ParkingYes

On-site or nearby parking available

Views

Lake
Mountains

Highlights

Jet Bath
Lukewarm Bath

About

Mantenboshi no Yu is a day-use onsen hall above Akaya Lake in Sarugakyo, Minakami. It has two bathing wings, an outdoor one with a stone garden and a lying-down soak, and a stone-floored, Western-style indoor one, and men's and women's sides swap between them by the day. The water runs mild rather than hot, there's a casual sauna and a cold bath side by side, and one of the outdoor tubs bubbles like a jet bath. Both baths look out over the lake and the mountains by day, and toward a wide stretch of stars once it gets dark. A private family bath can be booked separately. The bathing hall is part of a bigger grounds with a BBQ garden, a theater hall for taishu engeki (大衆演劇), a vegetable-picking farm, and a campground a few minutes away, plus a restaurant and a free rest lounge inside.

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Dinara

1 year ago

The design strongly reminded me of Station of Flower Katashina Hanasaku Hot Spring: similarly beautiful rotenburo with mountain views. Inside, besides the main bath, there's a sauna, a cold bath, and a nuryu (just lukewarm, pleasant — today they even put a bag of apples in it for good vibes). Outside there are several baths, one of them is a jacuzzi, and it's done really well. No photos at all since it was quite crowded, being Saturday. The water is mildly alkaline, pleasant, but with no color or smell. They say kashikiri (private baths) are available. Entry is 800 yen for 3 hours — at the entrance they give you a sign with the time, then you return the sign and get the shoe locker key. Tattoos not allowed. Inside there's a shop and various other entertainment and spa treatments.

Onsen Oni

Last updated July 30, 2026