Kōchi · Tosa & Usa
Tosaryu Onsen Sanyoso
土佐龍温泉 三陽荘
Forty minutes by car from Kochi city, a hot-spring inn beside Shoryuji, temple 36 of the Shikoku pilgrimage. It claims Kochi's only high-concentration, high-temperature spring; the golden chloride water is nicknamed 'the heat bath' for how long it keeps you warm. The rotenburo looks over Usa Bay and the Pacific, and there's a free seaside footbath. Day use in two sessions — 5:30–9:00 and 14:00–21:00 — ¥750 on weekdays.
- Price (adult)
- ¥750
- Hours
- 05:30–09:00 / 14:00–21:00(last entry 20:00)
- Closed
- Open daily
- Access
- 40 min by car from JR Kochi Station; 5 min by taxi from Usa bus stop
- Water type
- Simple spring
- Tattoos
- Ask ahead
- Phone
- 088-856-0001
- Official site
- sanyo-so.co.jp ↗
- Open in Google Maps
- Google Maps ↗
Essentials
Stay in this onsen town
Compare and book stays in Tosa & Usa. Day bathing itself needs no booking.
Opens partner booking site (affiliate)
Why go
- Kochi's strongest, hottest spring
- Pacific views from the rotenburo
- Day bathing from 5:30 am
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.
- Payment is usually by ticket machine in cash — bring coins.
- Last entry is 30–60 minutes before closing.
Features
Mood & scenery
Price
Who with
Convenience
Amenities
✔ Verified operating: 2026-09 こうち旅ネット 2026-01（平日750円/土日祝850円）
Prices and hours change. Check official sources before visiting.
More in this area
Sansuien Suisaikaku Onsen
The bath wing of a historic hotel built on the site of the Yamauchi lords' residence below Kochi Castle. A rare natural hot spring in central Kochi, with a rotenburo facing the Kagami River and Mt. Hitsuzan, a large indoor bath and sauna. Day use is daytime only, 10:00–16:00. Fifteen minutes on foot from Harimaya Bridge — easy between sightseeing and the Sunday market. ¥1,200; bring or rent a towel.
Hotel Matsubakawa Onsen (Shimanto)
A solitary inn on the Hinoji River in the Shimanto headwaters. Its viscous, highly alkaline water has been revered as a healing spring since the Edo period, and a day soak is a modest ¥700. Enjoy the open-air bath above the stream or book a private bath. Open late, 10:30–21:00, and 30 minutes by car from Kubokawa Station—ideal after canoeing or cycling the Shimanto.
Ashizuri Thermae (Ashizuri Onsen)
A design hotel on the headland at Cape Ashizuri, Shikoku's southernmost point, renewed in 2024. It holds one of the source wells of the Ashizuri hot-spring cluster — a natural radon spring, mildly alkaline, with a legend linking it to Kōbō Daishi — enjoyed in an open-air bath overlooking the Pacific, two indoor tubs and a Shimanto-cypress sauna. Sunsets into the horizon and the night sky are the draw. Day use 15:00–21:00 (last entry 20:30), ¥1,100 including bathing tax. Closed Tuesday to Thursday (with exceptions in peak season), so confirm ahead. About 90 minutes by bus from Nakamura Station, or an hour by car from Shimanto city. Combine with the cape lookout, the aquarium and the free Manjirō foot bath.