As a kata, I’ve long been fascintated by Naihanchin, and the possibilities this seemingly simplistic form provides us through its myriad of applications.
As a practitioner of Shorinjiryu karate, Naihanchin is usually one of the first forms learned. Yet the Naihanchin forms in Shorinjiryu differ markedly from those in most classical systems, with our forms having a lot more movement, including larger steps, and movement away from the lateral line. Many can’t see the connection between a Shorinjiryu Naihanchin and that practiced in other styles, without first seeing the missing link forms, such as Naihanchin no Sho (as taught in the Watanabe Ha lineage), and the Koshiki Naihanchin form introduced in the Kenkokan organisation.
Watching the Naihanchin 360 form shows that clearly the applications seen by many are more expansive than the base pattern lets on.
Similarly, the Naihanchin application used in the Kodo-ryu of Nathan Johnson sensei shows that the kata is very much a grappling form, at least from their perspective.
I’d be interested in hearing other perspectives on Naihanchin and its applications.