Ellis Amdur

Saigo Shiro was very active in nationalistic circles. John Steven's does a very good job in pulling together the available anecdotes on Kano Jigoro's history, including his inner circle. Very interesting information on Saigo.
A couple of points, however: the only assertion that yama-arashi was a modified shihonage was done by Obata Toshishiro--and he openly says in his writing that this is something he assumes.
If one refers to books written by Saigo's contemporaries (Yamashita, Mifune), they clearly list yama-arashi - it's a technique mid-way between tai-otoshi and harai-goshi. In the films of Hal Sharp, taken in the 1950's, several older teachers show this technique.
Interestingly, in Steven's book, based, I believe, on Kodokan records, Saigo was thrown out of the Kodokan because he loved to fight so much--street fights, but that he returned to visit Kano on occasion and was awarded, I believe, a 6th dan, in the 1920's.
Finally, a researcher in Japan as assiduously looked into the history of the Kodokan epic shiai against other ryu, and has found absolutely no newspaper accounts, and no written claims of these matches until decades later--well into the 1900's. Furthermore, there is no reference to Saigo having studied Daito-ryu or studied with Saigo Tanomo, until the 1920's. This researcher, a judoka, notes that these assertions are exactly contemporaneous with Ueshiba Morihei's advent as a teacher in Tokyo (and an examination of Takeshita's diaries show that what he was teaching was "how to defeat judo.").