>>1656304I feel A should be it's own story. Sure, it'd be a little similar to the Ghost Story, but you wouldn't have ghost magic, and there would always be the whole "failing at the worst possible time" gimmick.
For an added bonus, it could be a perverted lesbian girl, and add the typical "it doesn't make your CLOTHES invisible" gimmick, so when the device inevitably fails she'll be just as embarrassed as the girl's she was embarrassing.