The air force overflew Japan for weeks to put them off guard. 'Just another plane in the sky, nothing to concern yourself with,' until that last flight dropped the atomic bomb.
I hope Japan remembers this lesson: an enemy plane or missile in your airspace is not harmless. What happens when a NK missile, while overflying Japan, changes course and explodes in Tokyo?
Once the missile is over Japan, unless the Japanese Defense Force is on high alert and all systems are manned, up and running, and ready for action, the missile won't be stopped. And what if that missile has a nuke on board?
Anything entering Japan's airspace from NK must be shot down; anything less is inviting a tragedy of epic proportions. The leader of NK is not insane, he just doesn't care how many people end up getting killed. His father and grandfather let millions of NK's starve to death; does anyone think he cares how many Japanese might die?