The head temple of the Tendai Teramon sect. It was founded in the 7th century by King Otomo Yota, son of Emperor Kobun (Emperor Otomo), to mourn his father's passing. The temple's official name is "Nariyama Onjoji Temple. The temple was called "Mii no-dera" (temple of the well) because there is a sacred spring (well) in the precincts of the temple that was used for the births of the three emperors Tenchi, Temmu, and Jito, and thus the temple came to be called "Mitsui Temple. The temple is dotted with more than 100 national treasures and important cultural properties, including the Kondo Hall and "Mitsui's Evening Mirror," which is famous as one of the eight scenic views of Omi. The temple is also famous for its cherry blossoms and autumn leaves, which are illuminated at night in spring.