Otoku Onsen
Illustration photo — not a verified picture of this exact spot.
- Location
- Nakano, Nagano, Japan
- Water type
- thermal
- Temperature
- 40 °C
- pH
- 7.3
Water profile
Relaxing — deep, immediate muscle release.
Rich in trace elements — gentle on the skin.
Soft water — natural, classic buoyancy.
Otoku Onsen—Great Virtue Spring—takes its name from the highest aspiration of Japanese moral philosophy: otoku, the great virtue or exceptional benefit that arises from a life of integrity, generosity, and righteous action aligned with the deepest values of human flourishing. In the Japanese tradition of naming thermal springs for the moral and spiritual qualities their waters embody or bestow, a spring of Great Virtue represents a healing water whose benefits extend beyond the physical into the ethical and spiritual dimensions of the bather's renewal. Rising in Gunma Prefecture amid one of Japan's most thermally active volcanic landscapes, this spring offers its visitors the dual gift of volcanic mineral healing and the aspirational framing of bathing as a morally significant act of self-cultivation.