NIF

The NetImmerse File is a model format used by the Gamebryo (formerly NetImmerse) engine. It contains a model's meshes, skeleton, textures and stores its animations in external KF files.

Location
Most of Shin Megami Tensei IMAGINE's models are inside the /Avatar, /Devil, /NPC, /Map/Zone/Model and /effect/model folders.

Nifskope
A tool used to view, edit and overwrite the contents of a NIF file. It allows for material proprieties and texture changes, export the meshes as OBJ files and animation visualization. [| Link]