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Ryokan Masuya

箱根仙石原温泉 万寿屋旅館はこねせんごくはらおんせん まんことぶきやりょかん

Lodging

Day Use

Yes
10:30–15:30
¥900

Day-use bathing is 900 yen for adults, with towel rental included free of charge. A separate 150 yen bathing tax (nyutozei, 入湯税) applies to both day and overnight guests.

Bathing & Water

Natural onsen water

Uses natural hot spring water

Outdoor BathNo

Open-air outdoor bath

Site's own bath inventory lists only indoor baths, no rotenburo.

Indoor BathYes

Enclosed indoor bathing area

Capabilities

Private BathYes

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

Room OnsenNo

Private onsen bath in guest rooms, for overnight guests only

Mixed BathingNo

Shared bathing area for all genders

Policies & Services

WashingYes

Shower, wash stations, soap and shampoo provided

TowelsYes

Towels available to rent or borrow

Water treatment

Pure source water· 源泉かけ流し (gensen kakenagashi)
from Article 18 disclosure
  • Added water
    No
  • Reheated
    No
  • Recirculated
    No
  • Disinfected
    No
  • Bath additives
    No

大涌谷温泉 蒸気造成混合泉 2号線(仙石原方面)、3号線(強羅方面)

Owakudani Onsen Steam-Generated Mixed Spring (Line 2 / Line 3)

Operated by · 万寿屋旅館

Mixed source

Acidic
+ Sulfate · Chloride
Color
faintly milky-white turbid
Taste
not recorded
Odor
faint hydrogen sulfide
Hot source · 6°CUltra-acidicHigh silica
Known good for
  • Skin conditionsatopic skin, eczema
  • Circulationtired legs
  • Aches & jointsstiff shoulders
  • Sensitive-skin cautionbroken or dry skin

An acidic calcium sulfate-chloride spring generated from the volcanic steam of Owakudani. At pH 2.1 the water is sharp enough to sting slightly on contact, faintly milky-white and turbid, carrying a faint rotten-egg note of H₂S. It is well supplied with metasilicic acid at 157 mg/kg, leaving a thin silica film for noticeably smoother skin. It is served as untreated source flow — no dilution, heating, recirculation, or disinfection.

Analyzed Sep 28, 2018·神奈川県温泉地学研究所·Cert no. 神奈川県知事登録第1号

Explore the water

About

Ryokan Masuya is a small, old-fashioned inn in Hakone's Sengokuhara district, within easy reach of Lake Ashi and nearby hiking trails. It has just two indoor baths, one for each gender, filled with cloudy white sulfur water piped down from Owakudani (大涌谷) and kept running kakenagashi, straight from the source. Reviewers describe the water as slightly sour and slow to cool once you step out, with flecks of yunohana (湯の花) mineral sediment floating in it. Because there are only two baths, either side can be booked for private use by families or couples. The building keeps a plain Showa-era feel: guest rooms don't have their own bath or toilet, bedding is futon, and breakfast is a simple, home-style set.

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Reserve or check availability on a booking site.

Дмитрий Ракин

1 year ago

Once again following the footsteps of onsen-rush in Hakone, reaping the benefits for the second year now. A small Showa-style ryokan in Sengokuhara, Hakone. When I arrived, it looked closed and I had to call the old man on the phone, but he opened up and let me in. They're open every day. Still 900 yen. One bath that you can lock. The old man says families can use it together as kashikiri. The water is excellent: classic acidic sulfur of upper Hakone. Temperature is a bit on the hot side, you can dilute it. And it's all 100% kakenagashi. An unexpectedly lovely and charming ryokan with a great bath. The room itself is bright with a large window opening onto a garden, so it's essentially a semi-outdoor bath. Upgrading my recommendation to "must-visit in Hakone." https://t.me/jp_onsen/34096

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Sergey M
2 years ago

173. Ryokan Masuya, Hakone Visited for day-use bathing for 900, asked for a towel and they included it in the same price. Day-use hours are 10:30 to 16:00. Old-school ryokan in the northern part of Hakone, the building has that old damp smell. It seemed like the bath was private (the old man said you could lock the changing room). One small indoor bath with whitish-gray water, lots of white calcium deposits. Good air inside, practically no smell from the water. Temperature felt just above 42. For fans of that old-school vibe combined with interesting water — recommended. Otherwise — can be skipped.

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Last updated August 5, 2026