Yoshimi Onsen
- Location
- Yoshimi, Saitama, Kanto, Japan
- Water type
- sodium chloride
- Temperature
- 41 °C
- pH
- 7.3
Water profile
Relaxing — deep, immediate muscle release.
Loaded with major ions — the essential minerals (Ca, Mg).
Dense, salty water — you float without effort.
Yoshimi Onsen lies near one of Saitama Prefecture's most mysterious historical monuments — the Yoshimi Hyakuana, or Yoshimi Hundred Caves, a cluster of ancient rock-cut burial chambers carved into the tufa cliffs of the Musashino plateau during the late Kofun period (6th–7th century AD) by a community whose scale and organization of mortuary practice reveals remarkable sophistication for its era. More than 200 individual chambers have been identified in the cliff face, creating a haunting landscape of dark openings that scholars believe may have been used by Buddhist communities after the original burial function ceased. The onsen's mineral-rich spring waters provide a warm welcome for visitors exploring this extraordinary archaeological site, connecting ancient funerary water rituals to the living thermal tradition that continues in Saitama's subterranean geology.