Sadly I don't know how the game makes these edge lines. There is no texture for them.
There are awesome nude models of tsunade in the web. But the game needs the models in .xfbin format. And as far as I know there is no way to convert OBJ files to xfbin yet :(
Hmm head swaps. I have no clue how that"s done but I will try finding out when I got time. If it's possible this should be a possible way for a solution ;)
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I was just browsing the web for ''naruto shippuden ultimate ninja storm revolution nude mod'' I actually found one
Naruto Shippuden Nude Mod you should have seen my face when I realized that it's the one I made :D