How convenient.... He probably will want to register her as a Japanese citizen. She'll be in a big trouble if she's caught without any kinds of ID. Heck, she might be treated as an illegal alien (ugh, she is kind of like that though) and be deported to her "home country" which is troublesome, since they won't ever believe that she's from another world and therefore, they can't deport her using mundane technology. Welp, I might be wrong tho.