Gishin 義眞 (781–833), posthumously titled Shūzen Daishi 修禪大師 (“Great Master of Cultivated Meditation”), was the senior disciple of Saichō (最澄) and the first Tendai zasu 天台座主 (Tendai abbot, 824–833). Born in Sagami Province, he was ordained at Tōdai-ji and entered Saichō’s circle in 798. In 804 he accompanied Saichō to Tang China as his yakuhō 譯法 (translator-monk) — Gishin had advanced Chinese-language skills which Saichō, who was less fluent, relied upon to negotiate the doctrinal transmissions at Mt. Tiantai with Dàosuì 道邃 and Xíng-mǎn 行滿. Returning with Saichō in 805 with the Tiantai dharma-lineage, he was one of the first Japanese Tendai bhikṣus.
After Saichō’s death in 822 — and after Emperor Junnin’s 822 ratification of the Mahāyāna ordination platform at Hiei-zan — Gishin was appointed the first Tendai zasu by imperial proclamation in 824 and exercised oversight of the new institution. He performed the first ordinations on the Hiei-zan platform in 827. In 830 he composed KR6t0064 Tiāntái Fǎhuá zōng yìjí as the Tendai school’s contribution to Emperor Junna’s Tenchō imperial commission for doctrinal summaries — the formative statement of the Tendai school’s official doctrinal position.
Gishin’s tenure as zasu was marked by his careful institutional consolidation but also by his doctrinal conflict with Ennin (圓仁) and Enchō 圓澄 over the integration of esoteric (mikkyō) elements into Tendai practice; Gishin maintained the strict Tiantai-Lotus position, while Ennin and his successors developed the taimitsu 台密 esoteric synthesis. He died in Tenchō 10 (= 833 CE), aged 53 sui.
Within the Kanripo corpus his preserved work is KR6t0064 Tiāntái Fǎhuá zōng yìjí (830).