A hypertonic, strong-salt sodium chloride spring that also carries dissolved carbon dioxide and iron(II) — denser than seawater and leaving a thick mineral coating on the skin. The dissolved iron oxidizes reddish-brown on contact with air, the trademark look of Arima's 'kinsen' (gold) water. The certificate lists indications for poor circulation, sensitivity to cold, and dry skin.
Good for
Warming
Salt forms a film on the skin that slows heat loss, so the warmth lingers long after the bath (the classic heat-keeping water, nettō 熱の湯).
cold sensitivity
Cuts
Mineral-rich chloride, sulfate and sulfur waters have a long-recorded soothing effect on minor cuts and slow-healing skin.
minor wounds
Recovery
Warmth and buoyancy lower stress markers and improve sleep; habitual bathing is linked to lower rates of depression.
fatigue, stress
Take care
- Active phase of illness (especially when feverish)
- Active tuberculosis
- Advanced malignant tumors or severe physical debilitation such as marked anemia
- Severe heart or lung disease causing breathlessness on slight exertion
- Severe kidney disease with edema
- Gastrointestinal bleeding
- Visible bleeding
- Acute exacerbation of a chronic illness
Measured at the source
On the certificate
- Chronic pain or stiffness of muscles or joints (rheumatoid arthritis, osteoarthritis, lower-back pain, neuralgia, frozen shoulder, and the chronic phase of bruises and sprains)
- Muscle stiffness associated with motor paralysis
- Weakened gastrointestinal function (heaviness in the stomach, intestinal gas, etc.)
- Mild hypertension
- Impaired glucose tolerance (diabetes)
- Mild hypercholesterolemia
- Mild asthma or emphysema
- Hemorrhoidal pain
- Various stress-related symptoms (sleep disorders, etc.)
- Peripheral circulatory disorders
- Dry skin
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.
- Kario K et al. Hemodynamic Effects of Hot Spring Bathing. Hypertension Research 46(3):711–720, 2023.
- Naito Y et al. A Hot-Spring Water Improves Inflammatory Conditions in an Atopic Dermatitis Model. Biomedicines 13(11):2707, 2025.
- Takeda M et al. Hot spring bathing practices have a positive effect on mental health in Japan. Heliyon 9(9):e19631, 2023.