Sanno Shinto (山王神道)
Sanno Shinto (Sanno Shintoism) is a school of Shintoism developed by Hieizan Enryaku-ji Temple, the headquarters of Tendai Sect of Buddhism, from the end of the Heian period to the Kamakura period. In a narrow sense, Sanno Shinto is Shintoism before Tenkai in the Edo period.
Sanno' generally means a divine spirit that protects a divine mountain and, in this case, is Oyamakui no kami, the tutelary deity of Mt. Hiei. Sanno Shinto is the fusion of the worship of Oyamakui no kami (Sanno worship) and the Tendai Sect of Buddhism. Sanno no kami was also considered to be a manifestation of Buddha. The Chinese characters 'san' (山) and 'o' (王) are both composed of three straight lines and one line that crosses them, and this pictographic design was associated with the basic principle of Tendai Sect, or Sandai Sokuitsu (three truths taken as one single principle), for proliferation of the teachings.
Sanno Ichijitsu Shinto
Tenkai, a Buddhist priest in the Edo period who served Ieyasu TOKUGAWA, established Sanno Ichijitsu Shinto, a developed version of Sanno Shinto, after the death of his master and insisted the master's spirit be enshrined by the divine name of Gongen, an avatar of Buddha, according to the principle of Sanno Ichijitsu Shinto (aka Tosho Daigongen). According to Sanno Ichijitsu Shinto, Sanno Gongen is taken as Dainichi Nyorai (Mahavairocana) and Amaterasu Omikami (Sun Goddess). This idea is partly influenced by Ise Shinto (a school of Shinto thought established by priests of the Grand Shrine of Ise [Ise no Jingu] in the medieval period).