My understanding is that military fields around Tokyo eventually opened their runways to commercial flights - but eventually can be a long time if one is about to go min. fuel.
An interesting read - I was just looking at some Tech Log threads on definitions and calculations of reserve fuel, minimum fuel, when to call "PAN" or "MAYDAY" and such last night. This article was a perfect example of how they play out in the real world (I'll assume "real," for the moment.)