The Stone of the Medicine King

Formed by the eruption of the undersea volcano Mt. Ioi during the Miocene epoch of the Neogene period 15 million years ago, it became renowned for its ability to improve water quality due to the abundance of medicinal plants growing in the surrounding waters. Revered as a sacred stone since the Heian period, it is listed in the *Ioi-kan Yurimaki* as effective for treating stomachaches, burns, external injuries, and eczema. Since Mount Ioi venerates the Medicine Buddha as its principal deity, the Iō-ishi is also regarded as a representative stone of the Medicine Buddha. In 1985, the Iō-ishi was approved by Japan’s Ministry of Health, Labour and Welfare as a food additive (however, based on historical facts, it is not recommended for use as a medical product).