Tokusa Onsen

Minamiaizu, Fukushima, Japan

Location: Minamiaizu, Fukushima, Japan
Water type: silica, calcium-rich
Temperature: 40 °C
pH: 7.2

Water profile

Thermicity

Sedative

40 °C

LowHigh

Relaxing — deep, immediate muscle release.

Mineralisation

Restorative

LowHigh

Loaded with major ions — the essential minerals (Ca, Mg).

Buoyancy

Standard buoyancy

LowHigh

Soft water — natural, classic buoyancy.

SiliceSodiumBicarbonates

Tokusa Onsen in Fukushima Prefecture flows with siliceous, calcareous, and simple thermal waters, a triple mineral composition that combines the silky, skin-polishing effect of dissolved silica with the gentle mineral hardness of calcium carbonate and the universally accessible warmth of simple geothermal water, producing a multi-dimensional bathing experience of unusual mineral richness for a relatively lightly mineralized spring profile. Fukushima's volcanic heritage underlies a remarkable diversity of thermal spring mineral types, and Tokusa Onsen's three-mineral profile reflects the geological complexity of a prefectural landscape where volcanic, sedimentary, and metamorphic rock formations intersect in ways that produce spring water of exceptional variety. The spring embodies the layered mineral artistry of Japan's volcanic geothermal heritage, where the precise character of each spring's water tells the story of its specific geological journey through the strata of the earth before emerging at the surface.

Insider tip — Tokusa Onsen occupies a forested mountain valley in southern Fukushima, where silica and calcium-rich waters create exceptionally smooth bath water prized for its beautifying effects on the skin. The silica content gives the water a characteristic silky texture that feels almost viscous, a quality known in Japanese spa culture as bijin-no-yu or beautiful woman's water. Surrounding cedar and beech forests ensure the air stays fresh and cool even in summer. The small inn community here focuses on quiet contemplation rather than tourist facilities.

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