Kōin 光胤 (1396–1468) was a Muromachi-period Japanese Hossō 法相 (Yogācāra) scholar-monk affiliated with the Tōnan-in 東南院 — the Kōfuku-ji 興福寺 Hossō lecturer-residence institutionally housed at Tōdai-ji 東大寺. He stood in the late-medieval Kōfuku-ji “Northern Temple” 北寺 scholastic lineage and served as Yuima-e 維摩會 lecturer in his generation.
His two principal preserved works are both Hossō lecture-records on the Chéng wéishí lùn (KR6n0016):
- KR6n0019 Yuishikiron monsho 唯識論聞書 (T2264, 27 fasc.) — the formal lecture-transcript of his teaching cycle, recorded in Sino-Japanese kanbun-yomi with katakana glosses;
- KR6n0020 Yuishiki kunron nikki 唯識訓論日記 (T2265, 1 fasc.) — his personal study-diary on the same text.
Both are crucial witnesses to fifteenth-century Hossō scholastic practice in the Kōfuku-ji / Tōnan-in tradition and preserve the classroom register of Muromachi-Hossō teaching.
DILA Buddhist Person Authority A000318.