Stealing priceless artifacts and jewelry was an easy task for Dark Mousy. There was hardly anything to it at all. But stealing a box of tampons for a certain little 14 year old girl was of a different matter. There was a reason why only male members of the Niwa family could be a Phantom Thief and Dark couldn't wait for this generation to move on.
Sorry, I know its random but this weird idea popped into my head and I thought it was kind of funny.