Hoppo Onsen
- Location
- Iizuna, Nagano, Japan
- Water type
- thermal
- Temperature
- 38 °C
- pH
- 7.3
Water profile
Soothing — neither hot nor cold, perfect balance.
Rich in trace elements — gentle on the skin.
Soft water — natural, classic buoyancy.
Hoppo Onsen holds the distinction of being the first thermal spring discovered in the Shiga Kogen highland plateau of Yamanouchi-machi, Nagano Prefecture—a volcanic plateau that has grown into one of Japan's premier ski and onsen resort areas, encompassing dozens of springs and lodges across a vast highland landscape above the Joshinetsu Kogen National Park. Historically associated with the Yudanaka Shibu Onsenkyo cluster at the foot of the plateau, Hoppo was the original thermal foothold in a region where bathers can now ski in winter and hike volcanic peaks in summer while enjoying the surrounding waters. The honor of being Shiga Kogen's founding spring gives Hoppo Onsen a historical significance that transcends its mineral content—it is the origin point of an entire thermal resort culture in this celebrated mountain landscape.