Dual (or Ryobu, “Two-sided”) Shinto arose out of the early interaction between Shinto theology and Buddhist thinking newly imported from China. Some use the term ryobu shugo, “dual compromise,” to describe the resulting syncretism. Some accounts describe the developments this way: In 715 C.E. a Shinto shrine annexed a Buddhist temple. Twenty years later a smallpox epidemic created a crisis, to which the emperor responded by commissioning the colossal forty-eight-foot-tall bronze Great Buddha (daibutsu) at Nara’s Todaiji temple. At the same time, the ruler dispatched the Buddhist patriarch Gyogi to Ise shrine to seek the blessing of Amaterasu, the Shinto sun goddess. Gyogi secured a favorable oracle, and the next night the emperor had a dream in which Amaterasu identified herself as the Mahayana Buddha of Infinite Light, Vairocana. This laid the groundwork for further identification of the various kami (high beings) as alter egos of various Buddhas and Bodhisattvas.

In 750, an image of the Shinto war kami, Hachiman, was transported from its shrine at Usa on the island of Kyushu (just south of the main Japanese island, Honshu) to Todaiji in Nara so that the kami might pay respects to the Daibutsu. Hachiman thereafter remained in a shrine at Todaiji, where he became the guardian kami of Todaiji temple. Thus did a Shinto kami come to protect the teachings of the Buddha. This account reflects an interpretation formulated during the ninth century by teachers of a new esoteric school of Buddhism called Shingon. As always, this theological accommodation had its political implications and set the stage for many years of Buddhist growth and royal patronage. From then on until the Meiji Restoration in 1868, Dual Shinto was the dominant form of Shinto. With the Meiji Restoration of imperial power came increasing pressure from Shinto scholars to purge the tradition of all Chinese influences, including of course Buddhism and Confucianism, both of which had by turns exerted considerable pull at court for many years.