Tsubono Kosen

Tsubono Kosen is a historic mineral spring in Uozu City, Toyama Prefecture, also known as Tsubono Onsen or Tsubo-no-Kosen, with a tradition that traces the spring's discovery to a revelation associated with a statue of Yakushi Nyorai, the Buddha of Healing, carved by the legendary Buddhist monk Gyoki, reflecting the deep historical connection between water sources and Buddhist religious culture in Japan. The spring was developed as a formal bathing establishment from the early Meiji period when a physician named Hotta identified the mineral composition of the calcareous water, describing it as carbonated gold-character water, and established a bathing facility that opened as a proper hot spring establishment in 1956. Uozu City on the Toyama Bay coast is famous for the extraordinary phenomenon of mirage landscapes visible over the bay on spring days and for the abundant firefly squid that light up the dark Toyama waters each spring in one of Japan's most remarkable natural biological events.