星生温泉(蒸気泉)
Hoshisei Onsen (Steam Spring)Sodium-Calcium Sulfate-Bicarbonate spring
- Sodium Na⁺
- salt's cation — pairs with chloride to make the water salty.
- Sulfate SO₄²⁻
- "gypsum / Glauber's salt" — vessels and wound healing.
- Aches & jointsstiff shoulders
- Recoveryfatigue, stress
A remarkably hot steam-style source at 94.8 °C, classified as a simple thermal spring with neutral pH and a light mineral load. It sits among Japan's hottest natural sources — well above the 65 °C "top decile" line — and must be cooled substantially before bathing.