Eishin 英心 (b. c. 1264, date of death unknown) was a Kamakura-late-period Buddhist monk of the Shingon-Risshū 真言律宗 school of Saidai-ji 西大寺, the school founded by Eison (叡尊). The Taishō text KR6t0055 (Púsà jiè wèndá dòngyì chāo) preserves a colophon dated Tokuji 3 = 1308 CE in which the work’s compiler identifies himself as the Saidai-ji junior pupil Nyokū 如空, age 45 sui, working at the Zenkō-ji 禪興寺 in Echizen Province (Hokuriku). The CANWWW record and the work’s catalog entry identify the author as 英心 Eishin — the two names refer to the same person, “Eishin” being his Dharma name and “Nyokū” likely a signature variant. Birthdate is reconstructed from the age-45 colophon datum: 1308 − 45 + 1 ≈ 1264.
His one preserved work in the Kanripo corpus is KR6t0055 Púsà jiè wèndá dòngyì chāo, a systematic 32-heading question-and-answer compendium that constitutes the Saidai-ji school’s most polemically explicit early 14th-century defence of the Bodhisattva precepts against the rival positions of Shingon esoterics, Pure Land, Tendai yuándùn, and (especially) Zen. His Echizen location documents the propagation of the Saidai-ji Vinaya revival into the Hokuriku during the early Nanboku-chō period.
No CBDB or DILA Authority record currently locates this Eishin uniquely; he should not be confused with the homonymous Hossō scholar of Kōfuku-ji.