湯Simple
Ryumonzan Onsen in Kinokawa is classified as an alkaline simple thermal spring — gentle and low in irritation. Weakly alkaline and soft on the skin, it sits close to Japan's beauty-water family, leaving a faintly slippery feel. Lightly mineralized overall, it is the kind of mild water well suited to a long, unhurried soak.
Good for
Smooth skin
Bicarbonate and alkalinity gently lift dead keratin while silica hydrates, leaving skin smooth. This is the basis of the beautifying-water (bijin-no-yu 美人の湯) reputation.
dry, rough skin
Recovery
Warmth and buoyancy lower stress markers and improve sleep; habitual bathing is linked to lower rates of depression.
fatigue, stress
Measured at the source
pH
7.60
Weakly alkaline
Source temperature
25.1°C
Low temp.
Tonicity
0.32g/kg
Hypotonic
Flow rate
270L/min
Typical
Evidence
- Maeda M. 温泉の医学的効果とその科学的根拠. J. Hot Spring Science 70:197–207, 2021.
- Naito Y et al. A Hot-Spring Water Improves Inflammatory Conditions in an Atopic Dermatitis Model. Biomedicines 13(11):2707, 2025.
- Li H et al. Bicarbonate Ionized Water Bathing Enhances Natural Killer Cell Activity. Scientific Reports 14:51851, 2024.
- Takeda M et al. Hot spring bathing practices have a positive effect on mental health in Japan. Heliyon 9(9):e19631, 2023.