Eison 叡尊 (1201–1290), also known by his Dharma name Shien 思圓 and the posthumous title Kōshō Bosatsu 興正菩薩 (“Bodhisattva who Revived the True”), was a Kamakura-period Buddhist reformer and the founder of the Shingon-Risshū 真言律宗 (Shingon Vinaya School) centered at Saidai-ji 西大寺 in Nara. Born in Yamato into the family of a Kōfuku-ji priest, he entered the priesthood at age eleven and trained in Shingon doctrine at Daigo-ji 醍醐寺 under Eken 叡賢, but later turned to the precept revival being articulated by Kakujō 覺盛 (see 覺盛) at Tōshōdai-ji.
In the eighth month of Katei 2 (1236) Eison joined Kakujō, Ensei 圓晴, and Ugon 有嚴 in the famous self-vow ordination (ji-sei jukai 自誓受戒) ceremony, by which the four monks revived bodhisattva ordination outside the state-controlled three-master-seven-witness procedure. He took up residence at Saidai-ji in 1238, where he undertook a wide-ranging restoration of the dilapidated temple and built it into the institutional centre of the Shingon-Risshū. He revived nun’s ordination as well, ordaining nuns at Hokke-ji 法華寺 (Lori Meeks 2010 is the standard study).
Eison’s career was distinguished by sustained social-welfare activity — distribution of food, care of lepers (the non-jin 非人 community), bridge-building, and famine relief — and by his unique synthesis of Shingon esotericism with strict Vinaya observance, including reverence for Shinto deities and a programme of kanjō-style offerings to native gods. He was summoned twice (1262, 1273) to Kamakura by Hōjō Tokiyori and Hōjō Tokimune, and conducted the state-protection rituals against the second Mongol invasion of 1281.
Within the Kanripo corpus his works include: KR6t0053 Púsà jièběn zōngyào fǔxíng wénjí (1285) and KR6t0054 Yīnglǐzōng jiètú shìwén chāo.
DILA Buddhist Persons Authority: A001949.