Koyasan is an ancient temple complex located in Wakayama Prefecture, Japan. It is said to have been founded by the Buddhist monk Kobo Daishi in 816 AD. Kobo Daishi is credited with introducing the Shingon sect of Buddhism to Japan and establishing Koyasan as a center of Buddhist teachings. Since then, Koyasan has grown to become one of the most important religious sites in Japan, and is a popular tourist destination.