In the Shingon school of Buddhism, the name for the syncretic coexistence of Shinto and Buddhism (see Japanese religions). Ryobu Shinto and the other syncretic forms were banned 1868–1945 in favor of the new State Shinto.
The amalgamation of Shinto and Buddhism was officially instituted by the ritsuryo imperial edicts of the 7th and 8th centuries. The general term for the identification of Shinto kami with Buddhas and bodhisattvas is honji-suijaku. The theological basis of Ryobu Shinto lies in the writings of the Buddhist monk Gyogi (670–749) and the Shingon founder Kukai, also known as Kobo Daishi, (774–835). The Tendai school’s founder Saicho, or Dengyo Daishi, (767–822) also wrote on this subject, and the Tendai synthesis of Buddhism and Shinto is called Sanno-ichijitsu-Shinto.
In Ryobu Shinto, the sun goddess Amaterasu is identified with the Buddha Dainichi Nyorai; in the Tendai version, the Shinto kami of Mount Hiei are identified with various manifestations of the Buddha. Conversely, some Shinto shrines adopted Tantric Buddhist practices. Shinto kami guard Buddhist temples and vice versa.