This is very worrisome. Thank you for posting on it.
They would be yelling "Wuidehanryongdoja KimJong il dongji, Manse!" all the way it would seem--as impassioned as an "Allah Ahkbar!" Not out of the question.
I know of no air marshal system onboard Japanese aircraft and it's anybody's guess how soon the Air Self Defense Forces could scramble.
The Japanese are essentially not that good at crisis management, something big and entirely unexpected, which is very worrisome.