It's simple, Japan can either choose to go with China, the new great power in its region (which would be the most rational and non-violent choice), or it could choose to re-arm at the US's behest and risk direct military confrontation with the same China, which, of course, would be the violent choice (and hence the non-rational one).
That's what they get for having lost the last war in which they were involved, i.e. they get to play the music their victor is singing (also see the Plaza Accord).
That's what they get for having lost the last war in which they were involved, i.e. they get to play the music their victor is singing (also see the Plaza Accord).