>>4238614not sure about "extensive" but definitely some skill
might be doable in weaker programs like
paint.net>take real-world photo>layer 2: anime girl(s)>take bits of layer 1 that should occlude layer 2 (i.e., foreground objects) and move them to layer 3>make it look like the lighting in the scene is also affecting layer 2 (this is the hard part, but also what makes it look good)>export .jpg>profit 
