総合湯（混合泉）
Sogoyu (Blended Source)Mixed source
- Color
- colorless and transparent, with a slight amount of brown floating matter
- Taste
- not recorded
- Odor
- not recorded
Calcium-Sodium Sulfate-Bicarbonate-Chloride spring
- Calcium Ca²⁺
- settling and calming; can leave a white mineral bloom.
- Sulfate SO₄²⁻
- "gypsum / Glauber's salt" — vessels and wound healing.
- Aches & jointsstiff shoulders
- Circulationtired legs
- Warmingcold sensitivity
Sogoyu is Ikaho's blended source, and it reaches the bath as a calcium-led sulfate spring with bicarbonate softness layered in and a salty chloride edge. Moderately mineralized at 1,180 mg/kg, it has noticeable body without feeling heavy, and a generous 181 mg/kg of metasilicic acid puts it squarely in Japan's beauty-water family — the kind of silica film that leaves skin feeling smoother afterwards. At the spout the water is colorless and clear, carrying just a few flecks of brown suspended matter. The posted bathing indications run to neuralgia, muscle and joint pain, stiff joints, cuts and cold sensitivity; the wooden sign at the baths states the rotenburo is fed 100 percent free-flowing source water, arriving at 43.5 °C.
Analyzed May 30, 2017·群馬県薬剤師会環境衛生試験センター
