Chūjin 忠尋 (1065–1138), also known by the posthumous title Engyō Daishi 圓行大師, was a Heian-late-period Tendai master and the 47th Tendai zasu (1130–1138). Born in Yamato, he entered Mt. Hiei as a youth and trained in the Eshin school 惠心流 — the lineage of doctrinal teaching descended from Genshin (源信) — and became its leading mid-12th-century representative. He was appointed Tendai zasu in 1130 and served until his death in 1138.
Chūjin’s principal scholarly contribution was the documentation of the Tendai oral-transmission (kuden 口傳) tradition that had developed at Hiei-zan in the 11th and early 12th centuries. His KR6t0069 Hànguāng lèijù (compiled by 1128) is the most systematic surviving record of these kuden, covering the historical-doctrinal foundations of Tendai, the Taimitsu Sammon-Jimon controversy, the yuánjiào hongaku doctrines of inherent Buddhahood, and the Sannō Shintō honji-suijaku theology that was emerging in the contemporary mountain-cult tradition. The work is one of the principal documentary witnesses of the formative phase of medieval Tendai hongaku thought.
He is also remembered for his role in the Eshin-Danna school doctrinal controversies of the 12th century, mediating between the two principal Hiei-zan exegetical schools, and for institutional reforms during his abbacy.
Within the Kanripo corpus his preserved work is KR6t0069 Hànguāng lèijù.