Ripping android sprites from an obb file

[Gekko83]

So I'm trying to rip some sprites from an app (King of fighters 13) and I can't seem to access the obb file they're contained in. I tried changing the obb file to a zip but it wouldn't open and I can't really find anything online that's an alternative to that method so any help would be nice.

[Resistiv]

Can you send in the file?