Within what later came to be called Ryōbu Shintō, there is no single, closed canon that stands apart as a unique set of scriptures. Rather, this current rests on a web of texts drawn from both esoteric Buddhism and the classical Shintō tradition, read together through a syncretic lens. Central among the Buddhist sources are the Mahāvairocana Sūtra (Dainichi‑kyō) and the Vajraśekhara / Sarvatathāgata‑tattvasaṃgraha Sūtra (Kongōchō‑kyō), foundational to Shingon esotericism. These, along with related ritual manuals and commentaries, provide the doctrinal and ritual framework within which buddhas and bodhisattvas are correlated with particular kami. Tendai materials and the Lotus Sūtra (Hokke‑kyō) also serve as important supports, especially for articulating ideas of universal buddhahood and the status of kami as manifestations of enlightened beings.

On the Shintō side, the classical chronicles such as the Kojiki, the Nihon Shoki, and related mytho‑historical records are not abandoned but reread in light of esoteric Buddhist cosmology. Creation myths and kami genealogies are interpreted so that they resonate with mandalic structures and buddha–bodhisattva lineages, allowing the native deities to be seen as expressions of a deeper, universal ground. This interpretive strategy is closely tied to honji suijaku thought, which understands the kami as “manifest traces” of a more fundamental buddha‑reality. Shrine histories, origin legends, and other local records are likewise reinterpreted, so that specific shrines and their deities are aligned with the two great Shingon mandalas and their central figures.

Alongside these broader scriptural and historical sources, there also developed more explicitly combinatory writings that articulate Ryōbu Shintō doctrine in a focused way. Texts such as the Ryōbu Shintō shō and related tracts from Shingon lineages set out systematic equivalences between kami and buddhas, for example identifying Amaterasu with Dainichi Nyorai or reading major shrines as earthly counterparts of esoteric mandalic realms. Ise‑related Shintō writings, including works associated with the Watarai tradition such as the Shintō gobusho corpus, are shaped by these same esoteric hermeneutics. In this sense, what might be called the “primary texts” of Ryōbu Shintō are less a separate scripture than a constellation of Buddhist sutras, Shintō classics, and medieval doctrinal treatises, all woven together through a shared practice of reading the kami and the buddhas as two faces of a single sacred reality.