This kata emphasises on the training of tanden and upperbody without (much) use of the waist. (thus relying more on energy developed from tanden) Futhermore one should focus on the purpose of mahanmi and naihanchi dachi.
Ultimately Naihanchi is to develop one's internal muscle, which forms the 'basics' of Seishan and Chinto.
In other words, this kata teaches - or is training to develop - to generate energy from inside of the body to the outside
KATA