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Okazaki-so

岡崎荘おかざきそう

Lodging

Day Use

Yes
08:00–18:00
¥660

Adults 660 yen (as of April 2025); yumeguri (湯めぐり) ticket: 3 coupons.

Bathing & Water

Natural onsen water

Uses natural hot spring water

Outdoor BathYes

Open-air outdoor bath

Indoor BathYes

Enclosed indoor bathing area

SaunaNo

Dry heat sauna room

Capabilities

Mixed BathingNo

Shared bathing area for all genders

Policies & Services

DiningNo

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

WashingYes

Shower, wash stations, soap and shampoo provided

ParkingYes

On-site or nearby parking available

Water treatment

Pure source water· 源泉かけ流し (gensen kakenagashi)(partial disclosure)
from Article 18 disclosure
  • Added water
    No
  • Reheated
    Not disclosed
  • Recirculated
    No
  • Disinfected
    Not disclosed
  • Bath additives
    Not disclosed

下地獄5号泉・下地獄9号泉・下地獄16号泉 混合泉

Shimo-jigoku No. 5 / No. 9 / No. 16 Mixed Spring

Mixed source

Sulfur
+ Chloride · Sulfate

Sodium Chloride-Sulfate spring

Hot source · 87°CSulfur-rich
Composition fingerprint1.4 g/kg dissolved · Hypotonic
Na⁺86
Cl⁻53
SO₄²⁻34
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
  • Skin conditionsatopic skin, eczema
  • Circulationtired legs
  • Aches & jointsstiff shoulders
  • Sensitive-skin cautionbroken or dry skin

A blend of three Shimo-jigoku wells in Naruko Onsen, classified as a sulfur-bearing sodium chloride/sulfate spring. The wellhead runs at a scalding 87 °C and is delivered fresh-flow (kakenagashi) to both indoor and open-air baths. Carrying enough H₂S to fall into the sulfur-bearing family, the water has the characteristic rotten-egg note alongside a salty, mineral-rich body.

Sampled at mixing tank·Analyzed Jun 17, 2020·公益財団法人 宮城県公害衛生検査センター·Cert no. 11923

Explore the water

About

Okazaki-so is a self-catering toji-yado (湯治宿, a therapeutic-stay inn) in Naruko Onsen with no meal service and a shared kitchen. The baths are simple: an indoor bath and a small open-air bath, separated for men and women, fed by kakenagashi (源泉かけ流し, free-flowing spring water without recirculation). The water is clear with a faint sulfur smell. The outdoor bath closes in winter.

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SM
Sergey M
1 year ago

225. Okazaki-so, Naruko Onsen Visited on higaeri for 3 stickers on the local tegate (listed from 08:00 to 18:00). An old-timey place. There are even cobwebs on the upper baskets in the changing room. Indoor bath with clear water, temperature 41-42. Breathing inside is tolerable. Outdoor bath with no view, behind a fence. Water is clear but has some fine, sparse white lime deposits. Temperature 42.

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Last updated June 25, 2026