Softly use a hair-dryer on the plastic, make sure its not too hot to melt the plastic. But enough to melt the glue a tiny bit. If you did it right, the sticker rolls off cleanly leaving only a bit of glue left on the plastic, which is easily washed.
I've heard applying alot of water can help as well, although I generally have success with the hair-dryer trick.
Why must JRPG female leads suck so bad?







