Kamimoku Onsen

Nakanojo, Gunma, Japan

Location: Nakanojo, Gunma, Japan
Water type: bicarbonate, iron-rich
Temperature: 40 °C
pH: 6.3

Water profile

Thermicity

Sedative

40 °C

LowHigh

Relaxing — deep, immediate muscle release.

Mineralisation

Bio-active

LowHigh

Rich in active gases or metals — a strong mineral character.

Buoyancy

Standard buoyancy

LowHigh

Soft water — natural, classic buoyancy.

FerBicarbonatesManganèse

Kamimoku Onsen is located in Minakami Town, Tone District, Gunma Prefecture, and is sometimes included within the celebrated Minakami Juhachigyu — the Minakami Eighteen Hot Springs — a grouping that highlights the exceptional density of thermal resources in this region of the Japanese Alps. The spring flows with bicarbonate and ferruginous thermal waters, combining the skin-conditioning alkalinity of carbonate chemistry with the iron-rich mineral content that gives ferruginous springs their characteristic earthen quality and traditional association with strengthening the blood. Situated in one of Japan's most thermally abundant mountain valleys, Kamimoku Onsen offers visitors an authentic immersion in the layered geothermal heritage of Gunma, a prefecture where hot spring bathing is woven into the rhythm of daily mountain life.

Insider tip — Kamimoku Onsen in Nakanojo, Gunma Prefecture, combines bicarbonate and iron-rich mineral content in a pale amber-coloured water that stains the bath tiles a distinctive reddish hue. The iron gives a characteristic metallic tang to the steam and is associated with blood-enriching properties in Japanese balneology. The surrounding Agatsuma valley is famous for silk weaving and traditional craft villages, making a cultural day out easy to combine with an onsen retreat. Fewer foreign visitors reach Kamimoku than Kusatsu or Ikaho nearby, ensuring a genuinely local atmosphere.

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