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Kotohira Onsen Kotosankaku

ことひら温泉 琴参閣ことひらおんせん ことさんかく

Lodging
Shikoku·Kagawa

Day Use

No

Bathing & Water

Natural onsen water

Uses natural hot spring water

Outdoor BathYes

Open-air outdoor bath

Indoor BathYes

Enclosed indoor bathing area

SaunaYes

Sauna room of any kind

Bathing Arrangements

Private BathNo

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

Room OnsenNo

Private onsen bath in guest rooms, for overnight guests only

Several room types have their own private bath, but the site repeatedly states these in-room baths are not onsen water.

Mixed BathingNo

Shared bathing area for all genders

Baths are gender-separated with a morning men's/women's swap at 讃水館; no mixed bathing is offered anywhere on site.

Policies & Services

KidsYes

Welcomes children and families

WashingYes

Shower, wash stations, soap and shampoo provided

ParkingYes

On-site or nearby parking available

智光院温泉

Chikoin Onsen
Radon

Calcium-Sodium Bicarbonate spring

Cold mineral source · 19°CHigh radonHigh silicaCold mineral
Composition fingerprint0.3 g/kg dissolved · Hypotonic
Ca²⁺60
Na⁺25
Mg²⁺13
HCO₃⁻85
CationsAnions
Calcium Ca²⁺
settling and calming; can leave a white mineral bloom.
Bicarbonate HCO₃⁻
"soda" — softens skin, leaves it smooth.
Known good for
  • Aches & jointsstiff shoulders
  • Smooth skindry, rough skin
  • Recoveryfatigue, stress

Chikoin Onsen rises in Zentsuji as a simple, weakly radioactive cold mineral spring. Its 165.8 Bq/kg of radon places it squarely in the radon-spring family associated with the "hormesis" tradition, and comfortably past the level at which a spring is classed as therapeutically radioactive. Lightly mineralized at just 0.31 g/kg of dissolved solids and mildly alkaline, it is gentle on the body, while 64.1 mg/kg of metasilicic acid lends it a touch of Japan's beauty-water character. The source sits below 25 °C — a cold mineral spring — so it is heated before bathing.

Analyzed Jun 10, 2011·社団法人香川県薬剤師会検査センター

Explore the water

Views

Mountains

About

Kotosankaku is a large ryokan a five-minute walk from the approach to Kotohira-gu (金刀比羅宮), the shrine that gives the town of Kotohira its name. The property is split into two wings with separate baths. Sansuikan (讃水館) has the main indoor bath, a garden rotenburo and a sauna open to every guest in the hotel, with the men's and women's sides swapping each morning. Hitenkan (飛天館) has its own view bath on the tenth floor, Yakumo-no-yu (八雲の湯), reserved for guests staying in that wing, looking out toward Kotohira-gu and the hills around it. A few room types come with a private bath of their own, though the hotel is clear that those in-room tubs aren't filled with the spring water. It's a sizeable, somewhat old-school hot spring hotel rather than a quiet retreat: a big breakfast buffet, karaoke rooms, table tennis and a game corner sit alongside the baths. Reviewers describe a slightly retro, Showa-era feel to the building that's kept clean and well cared for.

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1 review

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RS
Rina Sergeeva
3 months ago· edited

A hotel in Kotohira, Kagawa. It tries to be a ryokan, using traditional motifs and materials, but the scale works against the idea. It consists of two buildings, each with its own onsen section. In the newer building (Sansuikan), the baths are located on the first floor and were available for day-use at the time of visit (no longer available now). In the older and more traditional building (Hitenkan), the baths and the panoramic rotenburo are on the top floor and offer a wonderful view, but are only accessible to Hitenkan guests. The source is weakly alkaline, pH 7.8, containing a little radon. The water is colorless, tasteless, and odorless. The main indoor bath in Sansuikan is hard to describe without using the word "pool" (it is claimed to be the largest in Shikoku). There are jets, two herbal baths, a sauna, and a mizuburo (cold bath). Outside in the garden, there is a charming stone rotenburo and a smaller bath (with a crowd of rubber ducks!). The vibe is specific. If you are looking for something intimate and cozy, this is definitely not your choice, but for a traditional wedding with a hundred guests, it’s just right.

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Last updated August 26, 2026