A gentle alkaline simple thermal spring, lightly mineralized and easy on the body. Its alkalinity gives the slippery feel of Japan's beauty-water family. Because the source runs cool, the water is reheated for bathing, served via recirculation and filtration, and disinfected with a chlorine-based agent. The facility's posted disclosure lists three tubs: a source bath kept at 34.5 °C, a medium bath at 38.0 °C and a hot bath at 41.0 °C, so the lukewarm source tub suits 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
Full composition
The bar is each ion's share of charge (mval%) within its group; over 20% names the spring. Gases, silica and trace metals are measured by mass only.
- Sodiumsalt's cation — pairs with chloride to make the water saltyNa⁺39.7mgP9 national78%
- Calciumsettling and calming; can leave a white mineral bloomCa²⁺9.7mgP25 national22%
- PotassiumK⁺0.60mgP7 national0.9%
- Magnesiummild; a laxative if you drink itMg²⁺0.09mgP6 national
- Aluminumshows up in acidic volcanic waterAl³⁺< —mg
- CopperCu²⁺< —mg
- Iron (II)rusts brown in air; iron for anemia when drinkableFe²⁺< —mg
- Iron (III)Fe³⁺< —mg
- Manganesetrace; companion to iron springsMn²⁺< —mg
- Bicarbonate"soda" — softens skin, leaves it smoothHCO₃⁻69.8mgP37 national51%
- Sulfate"gypsum / Glauber's salt" — vessels and wound healingSO₄²⁻35.4mgP37 national33%
- Chloridetable-salt anion — coats the skin and holds heat inCl⁻11.7mgP13 national15%
- Carbonatestrongly alkaline; slippery feelCO₃²⁻1.2mgP19 national2%
- HydroxideOH⁻0.09mgP39 national
- Metasilicic acidmetasilicic acid — a natural moisturizer for silky skinH₂SiO₃30.1mgP13 national
Measured at the source
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.