Tomitsu is Esoteric Buddhism that has been passed down in Shingon Buddhism. This term is used to differentiate it from Taimitsu, which is Esoteric Buddhism passed down in Tendai Buddhism. The name Tomitsu derived from the fact that the monk Kukai chose To-ji Temple as konpon dojo-seminary for Shingon Esoteric Buddhism.
It consists of two schools, Honyu School and Shusei School.
Under Tomitsu, Mt. Koya (Kongobu-ji Temple), To-ji Temple and Mt. Negoro (Negoro-ji Temple) are called the Three Great Centers of Learning. These three locations served as centers for training, research and advancement of the religion.
When the monk Kukai returned to Japan from Tang China in 806, he spread Shingon Buddhism around Toji Temple (present Kyoogokoku-ji) preaching that the only Esoteric Buddhism is the "gate of truth" to reach depth of "satori" (enlightenment). Shingon Buddhism later split into the Hirosawa school and the Ono school, which again multiplied into various sects.