Thank you friends for your information. I am also very sure that this Shin Kage ryu has nothing to do with the Koryu art of Yagyu Shinkage-ryu (or any other Shinkage-ryu for that matter). So, it must be a 20th century art. It can't be a gaijin production because in that book, Mr. Rielly has pictures of his Japanese teachers. So I think it's not his own creation. Too bad a friend borrow that book now. The name of his teacher escapes me. Later I will be back with the name of the publisher of the book, and the name of his teacher. One thing I remember is that Teruyuki Okazaki of Shotokan fame wrote a comment on the front cover, something like "this book is full with useful information".