湯Simple
A simple alkaline thermal spring feeding the Tokusa community bathhouse. At pH 8.45 it sits in Japan's beauty-water family with the characteristic slippery feel on the skin. Lightly mineralized and gentle on the body — a clean, unfussy soak rather than a heavily mineralized one, the kind of quiet alkaline water a community bath is built around.
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
On the certificate:Autonomic nervous system instabilityDepressed moodConvalescenceFatigue recoveryGeneral health improvement
Take care
Contraindications
- Active stage of any illness
- Active tuberculosis
- Advanced malignant tumor, severe anemia or other marked physical weakness
- Severe heart or lung disease causing shortness of breath on slight exertion
- Severe kidney disease with edema
- Gastrointestinal bleeding
- Visible bleeding
- Acute exacerbation of a chronic illness
Measured at the source
pH
8.45
Alkaline
Tonicity
Hypotonic
On the certificate
- Chronic muscle or joint pain or stiffness
- Muscle stiffness associated with motor paralysis
- Cold sensitivity
- Peripheral circulation disorders
- Reduced gastrointestinal function
- Mild hypertension
- Impaired glucose tolerance
- Mild hypercholesterolemia
- Mild asthma or emphysema
- Hemorrhoid pain
- Stress-related symptoms
- Sleep disorders
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.