who was this Jion character?

[Cliff Judge]

Draeger names him as the founder of Isshin Ryu in Classical Bujutsu.

William Scott Wilson, in his Introduction to his translation of Life-Giving Sword, says he founded Nen Ryu.

Tracing through some unannotated articles on Wikipedia, it looks like before he took the tonsure, his name may have been Sōma Shiro Yoshimoto.

Does anyone know of any other sources of information about this guy? It seems as though he may be an important ur-figure in japanese swordsmanship.

[Ellis Amdur]

Cliff - I write about him pretty extensively in Old School (http://www.edgework.info/buy-books-on-martial-arts.html).

The short version is that Jion was his name once he became a monk - Sōma Shiro Yoshimoto was his actual name.

He is a semi-legendary figure. That said, his role in the founding of Nen-ryu is probably central. His role as the founder of Isshin-ryu is more dubious. It is far more likely that Isshin-ryu, founded comparatively recently, appended a list of legendary figures to their lineage to give the school more prestige. The dates don't line up right, nor do the various figures in the early part of the lineage. One of the "proofs" of my assertion is that there is a several generation gap (just blank spots) in Isshin-ryu's lineage.

Donn Draeger was completely uncritical about the lineages/history of ryu he was most associated with. He simply reproduced the party line, without questioning it's logic.
Ellis Amdur