As we know, before creating Isshin-ryu, Master Shimabuku was extensively trained in Shorin-ryu, Goju-ryu and Kubodo (weapons.) Naturally, having mastered these areas meant that he was keenly familiar with the intricacies of each style. Through continual study, observation and practical application over the years, he began to find areas of deficiency in the Katas and fighting philosophy which, he felt, would leave a practitioner vulnerable to an attacker. Additionally, he noticed that training sessions often left students nursing injuries received from blocking and over extending arm joints. The consummate innovator, he always looked for ways to increase his punching and kicking power, and he found that many of the deep, extended stances he had learned often limited his mobility and ability to properly rotate his hips for power.
To overcome these weaknesses, he began to make modifications to the techniques he had learned. Gradually, his modifications began to transform the techniques; much like a woodcarver strips away the outer bark to reveal the carving within.
He figured out that subtle changes to a technique would often reveal a greater potential for power and create self-defense applications that were previously hidden due to limitations caused by body position.
When Master Shimabuku formed Isshin-ryu, he did so by “blending” the best techniques from both Shorin-ryu and Goju-Ryu, in addition to employing techniques that were unique to his own design. Taking what he learned from other styles, and molding it to fit his philosophy of what the ultimate fighting art should provide, Isshin-ryu is the living example of all the martial arts and life influences that were Tatsuo Shimabuku.
The 12 Features of Isshin-ryu Karate are as follows: