Onsen Iwasaki
Hot Spring Overview
Onsen Iwasaki is a small family-run minshuku in Yunoko Onsen, Minamata, Kumamoto Prefecture. Yunoko Onsen opened in 1925 and celebrated its 100th anniversary in 2025. The inn stands by the Shiranui Sea, and guest-room windows look over the hot spring town to the water. The owner is the captain of the fishing boat Akebono-maru.
The bath uses the inn's own spring, which flows through without added water, heating or recirculation. The water is a sodium bicarbonate-chloride spring (hypotonic, neutral, high temperature) with a source temperature of 51.2 C, and it is disinfected for hygiene.
The bath is an indoor tub small enough to fill with three people, with a jungle-like bath among trees at the back. There are five Japanese-style rooms, and dinner features fish landed that day. Day-use bathing is limited to the family bath at 1,500 yen, 14:00-20:00, by advance reservation only.
Hot Spring Details
| Quality | Sodium - Bicarbonate - Chloride Spring |
| Supply | Natural Source Flow |
| Heating | Not Heated |
| Dilution | Not Diluted |
| Filter | Not Filtered |
| Disinfect | Chlorinated |
| Drink | Not Drinkable |
| Source | 51.2℃ |
| Manage | Private Source |
Water Quality
Supply
Heating
Dilution
Filtration
Disinfect
Drinkable
Source Temp
Source Mgmt
Practical Info
| Stay | OK | ||||||||||||||||||
| Day Trip | OK | ||||||||||||||||||
| Fee | Adult 1500JPY/Child ---JPY | ||||||||||||||||||
| Hours |
|
Stay/Day Trip
Stay
Accommodation
Day Trip
Day Use
Admission Fee
Business Hours
| Mon | Tue | Wed | Thu | Fri | Sat | Sun | Hol | |
|---|---|---|---|---|---|---|---|---|
| 14:00 - 20:00 | 14:00 - 20:00 | 14:00 - 20:00 | 14:00 - 20:00 | 14:00 - 20:00 | 14:00 - 20:00 | 14:00 - 20:00 | 14:00 - 20:00 | 14:00 - 20:00 |
Booking
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Facilities
Access Information
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