Android .NPK extraction

So im trying to extract some models from an android game called Toaru Majutsu no Index
It has an interesting technique oh how they have done trees and id like to take a closer look at the model so i can effectively learn how to make my own

Iv attempted about 8 times to ninjarip this using the nox android emulator

Iv just extracted the APK and it seems all the asset files are in a .NPK format, so iv been googleling around and have found next to no references or info on this format

Dose anyone know anything about this what i assume is a .asset equivalent and how i might extract it, or is this something that is completely new?

Failing that is there a better android emulator to use for ripping if that effects anything?