Jichie 實慧 (786–847) was the principal disciple and chief institutional successor of Kūkai 空海 (空海) — the founder of the Japanese Shingon school. Known by his cloister-name Hinō 檜尾 (after his Mt. Kōya cloister) and posthumously titled Dōkō Daishi 道興大師.
Jichie entered Kūkai’s discipleship as a teenager and became one of the inner-circle disciples to receive the full dual-mandala Esoteric transmission from Kūkai personally. After Kūkai’s entry into eternal samādhi in 835, Jichie inherited the institutional headship of the Tō-ji 東寺 in Kyoto and was the principal figure responsible for the institutional consolidation of the Shingon school in its first post-founder generation. He oversaw the systematization of the lineage and the establishment of the formal succession at Tō-ji.
His KR6t0138 Āzì guān yòngxīn kǒujué 阿字觀用心口決 (“Oral Decision on the Mental-Disposition for the Letter-A Contemplation”) — explicitly headed “Hinō-ki” 檜尾記 — is the foundational text of the Aji-kan meditative tradition in the Japanese Shingon school. The work prescribes the precise meditative posture, mental-disposition, breath-regulation, and visualization sequence for the single-letter Letter-A contemplation that became the central meditative practice of medieval and early-modern Shingon devotional life.
The Aji-kan tradition thus founded by Jichie continues through the works of Jichihan 實範 (實範, cf. KR6t0144–KR6t0145) and the medieval Aji-kan literature, and remains a central meditative practice in the modern Shingon school.