Within Ryōbu Shintō, Fudō Myō-ō and other Buddhist deities are understood as the deeper, esoteric identities of the kami, articulated through the honji suijaku paradigm in which Buddhist figures are the “original ground” and Shintō deities their localized “manifest traces.” Rather than displacing the kami, these Buddhas, bodhisattvas, and Wisdom Kings provide a cosmic framework that situates indigenous deities within a broader mandalic universe. In this way, the Buddhist pantheon offers a language for interpreting the powers and functions of the kami, while the kami give concrete, place-bound expression to the otherwise vast and abstract Buddhist cosmos. The result is not a simple layering of one system atop another, but a mutual illumination in which each side reveals the hidden depth of the other.

Fudō Myō-ō is especially significant in this syncretic vision. As the immovable Wisdom King, he embodies fierce yet compassionate wisdom that destroys ignorance and subdues malevolent forces, a role that resonates strongly with the protective and purifying aspects of many kami. His wrathful form is read as an expression of a vow to protect practitioners, communities, and sacred spaces, and this same power is seen as the inner reality of kami associated with exorcism, boundary protection, and the pacification of harmful influences. Through this identification, Shintō rites of purification, warding, and oath-taking are framed within an esoteric Buddhist soteriology, so that concern for worldly safety and order is linked to the path of liberation from delusion.

More broadly, Ryōbu Shintō maps the Shintō pantheon onto the esoteric Buddhist cosmos, especially the mandalas centered on Dainichi Nyorai. Major kami such as Amaterasu are correlated with Dainichi, and Fudō Myō-ō, as an emanation of this cosmic Buddha, becomes the hidden aspect of martial and protective deities. This mapping allows shrines and their kami to be understood as nodes within the same sacred space envisioned in esoteric temple practice, so that shrine worship and mikkyō ritual are no longer separate realms but interpenetrating dimensions of one reality. In this shared space, Buddhist mantras, mudrās, and fire rituals directed to Fudō Myō-ō can be performed for the benefit of the kami, the land, and the community, while Shintō symbols and myths continue to shape the lived texture of devotion.

Through such identifications, Buddhist deities in Ryōbu Shintō serve both a doctrinal and a practical function. Doctrinally, they articulate a vision in which the protection of the state, good harvests, and other worldly blessings are not opposed to enlightenment but aligned with it, as expressions of the same compassionate activity that burns away ignorance. Practically, they legitimize and deepen traditional kami cults by embedding them in a universal salvific drama, without erasing their local character. The syncretic role of Fudō Myō-ō and related deities thus lies in holding together two religious worlds, allowing practitioners to move fluidly between them while sensing that both point toward a single, all-encompassing sacred order.