Emperor Keikō
The foundation of the Fujisan Hongū Sengen Taisha predates the historical period. Per shrine tradition, it was established in the reign of Emperor Suinin, with the shrine first built on its current location during the reign of Emperor Keikō. This was a period of intense volcanic activity on Mount Fuji, and the shrine was built in order to appease the "kami" of the mountain. The shrine is mentioned in accounts of the legendary hero Yamato Takeru as well. The entire mountain was off-limits for religious reasons, except for Shugendō monks noted for the asceticism.