When I try to post something similar, because I am in Japan, most DU'ers mumble something about Nanking as if that is all that needs to be understood about relations between Japan and China for now and forever. Forget my suggestion that the Chinese govt. uses Japan as a whipping post to stir up nationalism and avoid any criticism aimed at them.
There is tremendous backwardness in most of mainland China as you say. China, if I am right, is really 2 countries of enormous wealth and educational disparity. (Rural America VS. elite urban America an steroids)
Anyway, what you say about Japan's military is totally true. Only defense. But it is capable of defending itself pretty well is my guess.
I really think that Chinese govt. means to do nothing, but if they keep whipping up hatred, it may have uncontrollable results.