Nishiyama Onsen (Fukushima)
- Location
- Nishiaizu, Fukushima, Japan
- Water type
- calcium-rich
- Temperature
- 42 °C
- pH
- 7.3
Water profile
Relaxing — deep, immediate muscle release.
Loaded with major ions — the essential minerals (Ca, Mg).
Soft water — natural, classic buoyancy.
Nishiyama Onsen in Yanaizu-machi, Fukushima Prefecture, carries one of the most ancient documented founding dates in Japan's onsen tradition—717 CE (Yoro 1), making it a spring whose bathing history stretches to the Nara period when Japanese civilization was consolidating Buddhist influences that would define its culture for over a millennium. The spring complex comprises multiple sources of distinct mineral character—Kami no Yu, Shimo no Yu, Naka no Yu, Taki no Yu, Shin-yu, Ara-yu, and Oizawa among others—creating a mineral diversity within one Oku-Aizu highland resort that is unusual even by Japan's generous geological standards. Over thirteen centuries of continuous use, Nishiyama has evolved from an ancient bathing site into one of Fukushima's most historically weighted and culturally layered thermal destinations.