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Kaiun-no-yu

盛南温泉 開運の湯もりみなみおんせん かいうんのゆ

Bathing Complex
Tohoku·Iwate

Day Use

Yes
10:00–23:59
¥750

Adult ¥750; child ¥400; infant (2 and under) free. Early morning (Sat/Sun/holidays 6:30–10:00): adult ¥600, child ¥350. Ganbanyoku + pulgama add-on: +¥450. Sauna included in admission. Towel rental set ¥220. Cash only.

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

Policies & Services

TattooNo

Allows entry with visible tattoos

KidsWith Conditions

Welcomes children and families

Children 7 and over must use gender-separated baths.

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

Rest AreaYes

Relaxation space for after bathing

ParkingYes

On-site or nearby parking available

盛南温泉(開運の湯)

Seinan Onsen (Kaiun-no-yu)
Simple
+ 弱放射能泉

Sodium Chloride-Carbonate spring

High radonStrongly alkaline
Composition fingerprint0.2 g/kg dissolved · Hypotonic
Na⁺96
Cl⁻45
CO₃²⁻35
CationsAnions
Sodium Na⁺
salt's cation — pairs with chloride to make the water salty.
Chloride Cl⁻
table-salt anion — coats the skin and holds heat in.
Known good for
  • Aches & jointsstiff shoulders
  • Smooth skindry, rough skin
  • Recoveryfatigue, stress

A simple weak-radon spring rising in a residential pocket of Morioka. Strongly alkaline at pH 9.9, it has the slippery feel of the Japanese beauty-water family. Light overall mineralization (234 mg/kg dissolved solids) is offset by a notable radon load — 121 Bq/kg, well into the hormesis-tradition range. The wellhead runs at 31 C, so the bath is reheated for soaking.

Sampled at wellhead·Analyzed May 25, 2017·一般社団法人 岩手県薬剤師会·Cert no. 岩手県第1号

Explore the water

Highlights

Ganbanyoku

About

Seinan Onsen Kaiun no Yu (盛南温泉 開運の湯, "good-luck bath") is a day-use onsen complex in Morioka drawing natural spring water from underground. The bathing floor has indoor and outdoor pools, a carbonated bath, a radon bath, a sauna with cold plunge, and a private reserved bath (kashikiri, 貸切風呂) for small groups. An add-on ganbanyoku (岩盤浴, heated stone bed) and Korean-style pulgama steam room are available for an extra fee. A restaurant on the premises serves lunch and dinner.

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SM
Sergey M
1 year ago

212. Kaiun-no-yu, Morioka An aging onsen complex 4 minutes by taxi from Morioka Station. With a towel set it costs 970. There's massage, a dining area, a small shop. There's a private bath for 2200 and a stone bath (didn't try those). There were quite a few people for such a small place at 11 PM on a Sunday, but nobody bothered anyone. 1. Indoor area. 1.0. Breathing inside is comfortable, but there's a chlorine smell. 1.1. Smaller rectangular bath with clear onsen water, temperature around 40. Water is clear, noticeable chlorine smell. 1.2. Large rectangular bath with tap water enriched with some hard-to-translate thing - 高濃度 炭酸イオン泉 (high-concentration carbonate ion spring). Water is clear, smells like a mix of chlorine and something else, temperature 36-38. 1.3. Cold water bath. 1.4. Sauna. 1.5. In the passage between indoor and outdoor areas, a small square bath with clear warm water. Looks stagnant, I didn't understand its purpose. 2. Outdoor area. 2.1. Large stone bath with onsen water. A small bridge crosses over the bath. Water is clear, temperature 36-38, chlorine smell (but less noticeable than in the indoor bath). One side of the bath has a shallow area (about 1/4 of the total bath size). 2.2. Small elevated stone bath. Water appears to be tap water based on the diagram, clear, chlorine smell. Temperature 36-38. A questionable onsen. If you have very little time and need an onsen near the station, and chlorine doesn't bother you, then maybe. Otherwise, better to skip.

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Last updated June 25, 2026