But wouldn't the kids have the legal protections of their home/second nation extended to them? They might not be doing anything illegal under Japanese law, but they probably would under the other nations law. If the press got ahold of it, is there any politician in the world that wouldn't want the possible great press from "fighting" to let the mother or father of a little child get back their beloved from the clutches of a kidnapper, and a foreign one at that? Imagine the spin you could put on it. Headline stuff. Media is a powerful force in politics. Once it got that big, it doesn't matter if the foreign services want to deal with it or not, they would have to address it.

As from getting out of the country, get enough high placed people to push enough buttons and they could leave from any airport they choose, or, in the case of the US, airlifted to an military airbase.