Jion is the original
name, and the character for it has appeared frequently in chinese literature since ancient
times. The Jion-ji is a famous old Buddhist temple, and there is a well-known Buddhist
saint named Jion. The name suggest that the kata was introduced by someone identified with
the Jion Temple, just as the name of Shorin-ji Kempo is derived from its connection with
the Shorin Temple.
Caylor Adkins demonstrates Jion in 1976. Complete
video available here.