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Kamiyu

蔵王温泉 上湯共同浴場ざおうおんせん うえゆきょうどうよくじょう

Public Bathhouse
Zaō Onsen
Tohoku·Yamagata
023-694-9328zao-spa.or.jp

Day Use

Yes
06:00–22:00
¥300

Adults ¥300, children ¥100. Self-service cashier at the entrance, no staff.

Bathing & Water

Natural onsen water

Uses natural hot spring water

Outdoor BathNo

Open-air outdoor bath

Indoor BathYes

Enclosed indoor bathing area

Bathing Arrangements

Mixed BathingNo

Shared bathing area for all genders

Policies & Services

WashingNo

Shower, wash stations, soap and shampoo provided

TowelsNo

Towels available to rent or borrow

Rest AreaNo

Relaxation space for after bathing

ParkingYes

On-site or nearby parking available

大湯1号源泉

Ōyu No. 1 Spring

Operated by · 上湯共同浴場

酸
Acidic
+ 含硫黄泉 · Sulfate · Chloride
Hot source · 54°CUltra-acidicHigh silicaSulfur-rich
Known good for
  • Skin conditionsatopic skin, eczema
  • Circulationtired legs
  • Aches & jointsstiff shoulders
  • Sensitive-skin cautionbroken or dry skin

The Kamiyu community bath draws the Ōyu No. 1 source — an acidic, sulfur-bearing aluminium-sulfate-chloride water. It is sharp enough to sting slightly on contact, with the characteristic rotten-egg note of H₂S riding on top. Sulfate lends the water quiet body while chloride adds a salty edge, and the moderate mineralization makes it feel substantial rather than thin. Metasilicic acid at 226 mg/kg is unusually generous for a spring this acidic: behind the prickle it leaves the kind of thin silica film that Japan's beauty-water family is built on.

Analyzed Feb 10, 2009·株式会社丹野

Explore the water

About

The largest of the three communal baths (kyodo yokojo, 共同浴場) in Zao Onsen, Kamiyu sits in a wooden building at the top of the resort's main street. Men's and women's sides each have a single indoor tub, fed by a strong acidic sulfur spring that flows through continuously. There are no showers, no soap, and no amenities of any kind. You drop your coins in the unmanned box at the entrance, soak, and leave.

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Sergey M
7 months ago· edited

760. Kamiyu, Zao Onsen, Yamagata ★★ An old-school onsen for ¥300. The stated hours are 06:00 to 22:00. There is no staff, and there is no shower. The acidity of the onsen is so strong that even the stool in the changing room seems shocked. Indoor bath. The water is clear and acidic with a bluish tint, and there is lime scale on the bottom. The temperature is 43. Breathing inside feels great, but in January it is cold. A powerful old-school onsen, in winter it is cold, the acidic water has no shower, and the water is hot. Recommended for those who like a harsh atmosphere. 09.01.2026

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Last updated July 30, 2026