Within the tradition known as Ryōbu Shintō, the term “Ryōbu” (両部) literally signifies “two parts” or “two divisions.” This designation points directly to the dual structure at the heart of the system: the pairing of two great mandalic realms central to esoteric Shingon Buddhism. These are the Diamond Realm (Kongōkai) and the Womb Realm (Taizōkai), envisioned as complementary yet inseparable dimensions of the sacred. The very name of the tradition thus encodes a vision of reality as fundamentally twofold, yet ultimately integrated.

In this syncretic framework, Shinto kami are not set in opposition to Buddhist deities, but are instead interpreted as manifestations that correspond to the buddhas and bodhisattvas of these two mandalas. The Diamond Realm and the Womb Realm serve as the cosmological and symbolic matrix within which the Shinto deities are situated and understood. By mapping the kami onto this dual mandala structure, Ryōbu Shintō creates a theological bridge that allows Shinto worship to be harmonized with Buddhist doctrine. The term “Ryōbu” therefore does more than name a pair of realms; it signals a deliberate, systematic effort to see the many faces of the divine as expressions of a single, twofold sacred order.