Article by Emanuel Giordano

The kata of each Okinawan master have been slightly modified, over time, based on his martial experiences. Itosu sensei's kata obviously make no difference. As has already been amply demonstrated, Itosu sensei taught two types of Karate, one outside the world of public education, and one simplified and adapted for use within schools.
Over time, a widespread unsubstantiated belief arose, where Itosu sensei was labeled as the school Karate master, while two of his three main heirs, namely Yabu sensei and Hanashiro sensei, were seen as bulwarks of tradition. Recent discoveries have instead shown that they were very valid collaborators, and that they also adopted many modifications, some of which derived from Itosu sensei. From the words of Miyagi Hisateru sensei, written in his book Karate-do (1953), we know that although Itosu sensei was the senior teacher at the Shihan gakko, the teaching was almost entirely directed by Yabu sensei (to be succeeded by Tokuda sensei ). This obviously makes sense, given that teaching at this school began in 1906, and that Itosu sensei died in 1915. 
An interesting fact is that not everyone adopted the same modifications, and therefore teachers like Hanashiro, Yabu and Funakoshi taught slightly different kata. Leaving aside the modifications designed by Itosu sensei for Karate to teach to children (eg elimination of open hand techniques), which were only taught by Hanashiro, most of the variations were introduced only at Shihan gakko, where Yabu taught. This is also logical, if we think that the teachers who were trained within that school should then have also taught Karate in the various schools of Okinawa.
Hence, Yabu sensei taught the use of neko ashi-dachi / ukiashi-dachi instead of the "original" position, both in Pinan and in the other kata. He also taught an altered version of the kata Gojushiho, Passai (see articles: The Passai of Miyagi Hisateru - The Passai of Kotake Ieshiro), Kusanku (see article) and probably Naihanchi. Gojushiho since it, handed down from Toyama and Tokuda (version available in the book Shorin-ryu Karate: kata part 2), it is different from the "old" version, handed down by Hanashiro; Passai because, as demonstrated in the aforementioned articles, it is a simplified version of Itosu no Passai; and Kusanku for the same reasons.
Coming to the Pinan, research has momentarily managed to find only two of the five kata taught at this school, which turn out to be simplified versions of those that Itosu transmitted outside the scholastic world to Chibana sensei (available in the book Shorin-ryu Karate: kata). The evolution of the Pinan shodan (Heian nidan) has already been presented in a previous article, while now I'm going to talk about Pinan nidan (Heian shodan). Given the extreme simplicity of this form, the changes could not have been many. 
Let's take the version handed down by Chibana sensei as a reference outside the school world: the main characteristics are represented by the first technique, an otoshi tetsui instead of a gedan-barai; from the fact that all tsuki are jodan; and from the fact that the final four techniques are gedan-shuto. This version, therefore, has two otoshi tetsui: one facing left (at the beginning) and one facing right, performed after the right gedan-barai.  
The version handed down by Funakoshi sensei, which was already a school version, however: begins with a gedan-barai; has all the tsuki chudan; the last four techniques are chudan shuto. This version has only one otoshi tetsui, on the right, performed after the right gedan-barai (video).
The most recent version, however, was the one taught by Yabu sensei: the kata is identical to that of Funakoshi sensei (except for the use of ukiashi-dachi instead of kokutsu-dachi, although the name used is always the latter), but it has no otoshi tetsui. This version is described with images and captions in the books Karate-do (Miyagi Hisateru, 1953) and Anata no mi o mamoru zukai setsumei Karate gokui kyohan (Kotake Ieshiro, 1955). In the attached photo you can see an excerpt.
With this, the difference between Itosu's school Karate and the Karate he broadcast outside of schools was again demonstrated, but also demonstrated the simplification of school kata over time, as well as the great attention paid to those who would lead forward the project of the introduction of Karate in schools, ie the students of Shihan gakko.
  • "Shorin-ryu Karate: kata 2" (here)
  • "Shorin-ryu Karate: kata" (here)
  • "Shorin-ryu Karate: The legacy of the bodyguards of the king of Okinawa" (here)
  • "The legend of the masters of Okinawan Karate: Biographies, curiosities and mysteries"  (here)