Ryōbu Shintō and Sannō Shintō can be seen as two distinct yet related ways in which the Japanese religious imagination wove kami and buddhas into a single fabric, each grounded in a different Buddhist lineage and institutional setting. Ryōbu Shintō is rooted in Shingon esoteric Buddhism and takes its very name from the “twofold” mandalas of the Womb World and Diamond World, using this dual-mandala structure to organize and interpret the kami. Within this vision, major deities such as Amaterasu and Toyouke are correlated with Dainichi Nyorai, the cosmic Buddha, and other esoteric figures, so that the Shinto pantheon is read as a differentiated expression of a single, all-encompassing Buddha-body. Sannō Shintō, by contrast, arises from the Tendai tradition at Mount Hiei and centers on the Sannō, the “Mountain King” kami of the Hie Shrine complex, who are treated as manifestations and protectors aligned with Tendai’s principal buddhas and bodhisattvas. Here the focus is less on a universal mandalic cosmos and more on a shrine-centered system in which local guardian deities embody the Dharma and safeguard the mountain, the temple, and the political center.

Both systems work within the broader logic often described as honji suijaku, understanding kami as manifestations or trace appearances of buddhas and bodhisattvas, yet they inflect that logic differently. Ryōbu Shintō leans into a strongly esoteric orientation, employing mandalas, mantras, and ritual symbolism to assert a non-duality between buddhas and kami, so that shrines, landscapes, and even imperial authority can be mapped onto Shingon’s cosmic vision. Sannō Shintō, drawing on Tendai’s doctrinal frameworks and especially its Lotus Sutra–based outlook, retains a clearer hierarchy in which buddhas are the original ground and the Sannō kami are their provisional forms, emphasizing their role as tutelary powers. In this way, Ryōbu Shintō tends toward a broad, cosmological synthesis that reaches across the realm, while Sannō Shintō remains more tightly bound to the sacred geography and institutional life of Mount Hiei and its shrine-temple complex. Both, however, testify to a religious world in which the boundaries between kami and buddhas are porous, and where different Buddhist schools offered distinct yet overlapping maps for traversing that shared sacred terrain.