Kira Onsen
- Location
- Kira, Aichi, 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.
Kira Onsen is a hot spring in the Kira area of Nishio City, Aichi Prefecture on the Mikawa Bay coast of the Kii Peninsula, an iodine-rich coastal spring associated with the historical memory of the feudal lord Kira Kozukenosuke, whose killing by the forty-seven ronin samurai in 1703 inspired one of the most celebrated tales of loyalty and revenge in Japanese culture. The onsen gained notoriety in recent decades when it was involved in a hot spring fraud case, where water did not meet the regulatory standards for a genuine natural hot spring, but the facility subsequently reformed its practices and now draws on a certified new spring source in compliance with the Japanese Hot Spring Law. The iodine-bearing waters of the reformed Kira Onsen, situated along the scenic Mikawa Bay coast within the Mikawa Bay Quasi-National Park, provide therapeutic bathing in a setting enriched by the historical legends and marine landscapes of this culturally resonant corner of Aichi Prefecture.