Kagawa · Kan'onji & Kotohiki Park
Kotohiki Kairō open-air bathhouse, Kan'onji
讃岐路野天風呂 湯屋 琴弾廻廊
A Japanese-style spa right by Kotohiki Park in Kan'onji, western Kagawa — famous for the giant coin drawn in sand, the Zenigata Sunae — and directly in front of Ariake beach. Its baths are inventive: a 'seawater onsen' bath, an ancient-cypress bath and a kama-buro steam bath recreating a 1,200-year-old design (alternating men/women daily), and the open-air bath looks over the Seto Inland Sea toward the sunset. Adults ¥950 on weekdays, ¥1,100 on weekends and holidays; open 11:00–23:00 (last entry 22:00), every day of the year. A sea-view restaurant, indoor and outdoor rest areas and lodging are attached. About 5 minutes by car from JR Kan'onji Station or 15 from Sanuki-Toyonaka IC; 500 parking spaces. Combine with the Chichibugahama sunset and the sand coin.
- Price (adult)
- ¥950
- Hours
- 11:00–23:00 (last entry 22:00)
- Closed
- Open daily
- Access
- About 5 min by car (25 min on foot) from JR Kan'onji Station; about 15 min by car from Sanuki-Toyonaka IC
- Water type
- Simple spring
- Tattoos
- Ask ahead
- Admission
- Admission adults (junior high and up) ¥950 weekdays / ¥1,100 weekends and holidays, elementary ¥550/¥650, preschool ¥350/¥450 (revised October 2024), ¥100 off for JAF members. Towel set rental ¥300, shampoo provided, lockers free, free Wi-Fi, cards and PayPay accepted. Bedrock bath (extra), private family bath (charged, reserve), restaurant (raw jako shrimp, straw-seared bonito, Sanuki udon), lounge with manga, body care. For sauna fans: '11 saunas and 7 plunge pools' (men's and women's combined)
- Baths
- A large day-use onsen in Kan'onji at the western tip of Kagawa, right beside Ariake beach on the Seto Inland Sea and the giant 'Kan'ei Tsuho' coin sand sculpture (viewed from Kotohiki Park). Known as one of Shikoku's 'sauna meccas' for its sea-facing 'Sanukiji open-air bath' and a combined 11 saunas and 7 plunge pools across the men's and women's sides. A restaurant serving fresh Inland Sea seafood (raw jako shrimp, straw-seared bonito). Combine with temples 68 and 69 of the Shikoku pilgrimage (Jinnein and Kan'onji) and Chichibugahama, the Instagram-famous 'Uyuni salt flat' reflection beach, 15 min by car
- Spring water
- Kotohiki Kairo Onsen, a sodium-calcium chloride spring (weakly alkaline, hypotonic; the 30°C-range source from 1,500 m down is heated and recirculated). Pale yellow-brown clear water, faintly salty and heat-retaining; the outdoor 'source bath' is minimally heated. Indicated for neuralgia, muscle pain, poor circulation, cuts, dry skin and fatigue. The high-concentration carbonated bath (artificial) boosts circulation. Plunge pools come in seven temperatures from 5 to 17°C (men's and women's combined)
- Access & parking
- 5 min by car or about ¥1,000 by taxi from Kan'onji Station on the JR Yosan Line, or 25 min on foot (city bus to 'Kotohiki Koen' then 5 min on foot; few services). 1 h by train from Takamatsu, 1 h 10 min by limited express from Okayama. By car 20 min from Sanuki-Toyonaka IC or 15 min from Onohara IC on the Takamatsu Expressway, 1 h from Takamatsu, 1 h 40 min from Matsuyama. Free parking for 500. Kotohiki Park lookout (coin sand sculpture) 10 min on foot, Chichibugahama 15 min by car, Kan'onji and Jinnein temples 15 min on foot
- Phone
- 0875-24-4567
- Official site
- kotohiki-kairo.co.jp ↗
- Open in Google Maps
- Google Maps ↗
Essentials
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Why go
- On Ariake beach, sunset over the Inland Sea
- Seawater bath and a 1,200-year-old steam bath
- Pair with the sand coin; open daily
A rotenburo facing the Inland Sea and eleven saunas — the sauna mecca of western Shikoku
Sanukiji Open-Air Bath Yuya Kotohiki Kairo is a large day-use onsen in Kan'onji at the western tip of Kagawa, right beside Ariake beach on the Seto Inland Sea and Kotohiki Park, famous for its giant sand sculpture of an Edo-period 'Kan'ei Tsuho' coin. True to its name, the open-air bath faces the sea so you soak looking out to the islands and sunsets of the Inland Sea, and the pale yellow-brown chloride water from 1,500 m underground is faintly salty and highly heat-retaining. What made it famous nationwide, however, is sauna: a combined eleven saunas across the men's and women's sides (high-heat dry, loyly, steam, salt, self-loyly and more) and seven plunge pools from an extreme 5°C up to 17°C, earning it the titles 'strongest in Shikoku' and 'sauna mecca' among enthusiasts, not a few of whom cross from Honshu just for it. The restaurant serves fresh Inland Sea seafood — Kan'onji's speciality raw jako shrimp (a sashimi of a small lobster relative), straw-seared bonito and Sanuki udon — and with a lounge, manga, bedrock baths, a private family bath and Wi-Fi it is a place to spend the whole day. At ¥950 on weekdays and ¥1,100 on weekends and holidays it is cheap for the number of saunas, open 11:00–23:00 every day of the year. Five minutes by car from Kan'onji Station and an hour from Takamatsu, the golden course for western Kagawa is to view the coin sand sculpture from the Kotohiki Park lookout ten minutes' walk away (legend says seeing it frees you of money worries), shoot 'Uyuni salt flat' reflections at low tide at Chichibugahama fifteen minutes by car, then bathe after sunset.
How to work through eleven saunas and seven plunges, and the seaside rotenburo
Park in the large car park along the Ariake beach road, pay admission at reception (¥950 on weekdays) and receive a locker-key band; in-house charges are settled on exit (towel set ¥300 to rent, shampoo provided). Indoors are a main pool, high-concentration carbonated bath and jet bath; outdoors the sea-facing 'Sanukiji open-air bath', a source bath and pot tubs, with the pines of Ariake beach and the Inland Sea spreading beyond. The stars, however, are the saunas — five or six on each side with three or four plunge pools arranged around the outdoor area. A recommended circuit: (1) wash and pre-warm in the carbonated bath; (2) 8–10 minutes in the high-heat dry sauna (90–100°C, auto-loyly on the hour); (3) plunge progressively — start with the 'normal' 15–17°C pool, then the 10°C range once accustomed, and finally the 5°C 'extreme cold' (not for weak hearts); (4) cool down on an infinity chair in the outdoor sea breeze; (5) switch between the self-loyly sauna (ladle aroma water on the stones yourself), steam and salt saunas for three or four sets. Sit in a cool-down chair at sunset (around 19:00 in summer, 17:30 in winter) and the sun sinks into the Inland Sea straight ahead — what enthusiasts call 'Kotohiki's golden hour'. The onsen itself is a pale yellow-brown chloride spring, most authentic in the outdoor 'source bath', whose heat retention makes a good finish after the sauna sets. The restaurant offers Kan'onji's raw jako shrimp sashimi (seasonal, subject to catch), straw-seared bonito, Sanuki udon and sauna drinks such as 'oropo' (Oronamin C with Pocari). Crowds peak 15:00–21:00 on weekends with queues for popular saunas, so weekday afternoons or the 11 a.m. weekend opening are more comfortable; observe sauna etiquette (sit on a towel, rinse sweat before plunging, keep conversation down). Note that tattoos are not permitted.
Practical details and a western Kagawa route
Hours are 11:00–23:00 (last entry 22:00), open year-round (maintenance closures announced); adults ¥950 weekdays / ¥1,100 weekends and holidays, elementary ¥550/¥650, preschool ¥350/¥450, ¥100 off for JAF, towel set ¥300, bedrock bath and family bath extra, free parking for 500. Access is 5 minutes by car (taxi about ¥1,000) or 25 minutes on foot from Kan'onji Station, 1 hour by train from Takamatsu, 1 h 10 min by limited express from Okayama, or 20 minutes by car from Sanuki-Toyonaka IC. Suggested routes: (1) a western Kagawa day — Kan'onji and Jinnein temples in the morning (pilgrimage temples 68 and 69, two temples in one precinct), the Kan'ei Tsuho sand sculpture (345 m around) from the Kotohiki Park lookout, Sanuki udon for lunch ('Tsuruya' and others in town), reflection photos at Chichibugahama in the hour around low tide and sunset (check tide times on the Mitoyo tourism site), then saunas and dinner at Kotohiki Kairo until night, on to Takamatsu or a local stay; (2) a sauna expedition — cross from Honshu via the Seto Ohashi bridge and Okayama by limited express, conquer all eleven saunas in a day and stay in Kan'onji; (3) with the Shikoku pilgrimage — bathe between temple 67 Daiko-ji, 68–69 and 70 Motoyama-ji (five-storey pagoda); (4) families — a daytime walk on Ariake beach and Kotohiki Park, the onsen, then a raw jako shrimp dinner. Notes: the 5°C extreme plunge is off-limits for heart conditions, drinkers and children; weekend evenings are crowded; tattoos not permitted; Chichibugahama reflections need low tide, no wind and sunset to coincide, so check the tide table; raw jako shrimp sells out depending on the catch. Kotohiki Kairo is less an 'onsen facility' than 'a sauna theme park with a sea view', so non-sauna visitors should set expectations around the rotenburo and the food.
Before you go
- No official tattoo policy is published — ask at reception.
- Ryokan day-use hours are limited and may be suspended in peak season — phone the same morning.
- Last entry is 30–60 minutes before closing.
Features
Mood & scenery
Sauna & wellness
Price
Amenities
✔ Verified operating: 2026-09 Operating status and rates cross-checked against the official site and onsen guides (full source notes in Japanese on the JA page)
Prices and hours change. Check official sources before visiting.
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