Cuó’é 嵯峨 (Saga tennō)
Fifty-second emperor of Japan (r. 809–823); patron of 空海 Kūkai and founding sponsor of the early Shingon school. In Kōnin 9 (818), during a great plague, Saga personally copied out the Heart Sūtra in gold ink on indigo paper as a state apotropaic ritual, with Kūkai composing the Hannya shingyō hiken (KR6c0199) as the accompanying ritual-doctrinal commentary. The episode established the long-running Heian-court pattern of imperial sūtra-copying paired with Esoteric Shingon ritual exegesis as state defense against plague and disaster.