Kotoku-ji Temple, built on Mt. Koshin-san, is a temple of the Tendai sect of Buddhism belonging to Hiei-zan Enryaku-ji Temple. It is known as one of the three sacred mountains in the Koka area, along with Mt. Hando-san and Mt. Iwao-san.
Because of its legend concerning the origin of brass, Kotoku-ji Temple attracted the faith of hardware dealers in Edo (present day Tokyo), Kyoto, and Osaka during the Edo era. Non-ferrous metalworkers from all over Japan continue to visit the temple to this day.