Japan doesn't have a military. All they have is a self defense force. Of course, it takes a lot to defend yourself when you are face-to-face with China, North Korea and Russia.
I am not sure of the distinction. Do they not spend funds on offensive weapons? Do they have fighter planes, long range bombers? Japan is entitled to defend its borders as any other nation. Why is their defense not military as you stated?
From this article it sounds like their current navy and air force could very likely defeat the PRC without any US help:
http://www.strategypage.com/dls/articles/2005512213835.asp
Of course, their constitutional emphasis upon "self-defense" means they would be very unlikely at present to help defend Taiwan or South Korea, but if the threat from the PRC keeps growing (and it will) that may change perceptions and politics in Japan quite a bit.