Jōshin 定深 — Mid-to-late Heian-period Japanese Shingon scholar-monk. His lifedates are not preserved in the canonical record; the terminus ante quem for his floruit is established by the 1198-CE 東寺假堂 transcription colophon of his Qiānshǒu jīng èrshíbā bù zhòng shì (KR6j0261, T61n2243), so he was active no later than the late 12th century.
His extant works in the Buddhist canon are:
- Qiān-shǒu jīng èr-shí-bā bù zhòng shì 千手經二十八部衆釋 (KR6j0261, T61n2243) — a one-fascicle commentary identifying and explicating the twenty-eight retainer-deity classes attached to Avalokiteśvara in the Thousand-Hand Avalokiteśvara cult, drawing on both the old (古本) and new (新本) recensions of the Qiān-shǒu jīng and on the now-lost Tang commentary in three fascicles.
- Shíbā qì yìn yì shì shēngqǐ 十八契印義釋生起 (T2475 in Taishō Vol. 78; not in Kanripo) — short doctrinal-ritual treatise on the eighteen mudrā signs used in the Shingon eighteen-stage ritual (jūhachidō kanjō practice).
The combination of these two works — a Qiānshǒu commentary and an eighteen-mudrā ritual treatise — places Jōshin firmly in the scholastic-ritual mainstream of mid-Heian Shingon practice.
Source: DILA Buddhist Person Authority A000613.