I took a quick look at the preview of a book called "Shotokan Mysteries: The Hidden Answers to the Secrets of Shotokan Karate". Scrolling down to see if I might be interested in purchasing the Kindle edition, I read a section discussing the reason for the frequent use of back-stances (kokutsu-shitsu dachi - bent rear-knee stance). The author states that the back-stance is a development of Master Gichin Funakoshi's, based on his "encounter" with Master Kano Jigoro's judo-ka. Whatever the demonstration actually contained, what the author says is not true, and not based on research, but on theory. Master Funakoshi developed many of the kata to be his own versions, and in some cases, to be essentially his own creations entirely. This is largely based on his studies under various teachers, principally including Masters Asato and Itosu. Combining the teachings of both of these lineages resulted in the kata devised and the new versions of kata developed by Itosu, to be altered and developed with the inclusion of the teachings of Master Sokon Matsumura's lineage through Asato, primarily, besides directly from Matsumura. In Matsumura's school, it can be observed that the back-stance exists prominently, proving my point. These changes were made by Funakoshi while he resided in Okinawa before the 1920s, and probably long before, since he was teaching karate in Okinawa for around 15 years before moving to mainland-Japan.
