Probably the best thing Japan could do is give the Chinese a significant distraction away from the area. The nature of this distraction would almost have to be the loss of a significant, tangible asset for China.
And quite certainly, this distraction would have to have plausible deniability for the Japanese. Something under the heading of “bad luck” for the Chinese. Very bad luck.
You wouldn't be hinting at the floating 'casino' would you?