You can't see geopolitical interests, it is your problem that your TV doesn't say about it. And seems you don't know anything about what a huge cooperation Russia and China have. If China would begin a war, they would destroy Japan first.
Except war with Japan would give them nothing. No land that they desperately need, nothing. Only thing they would get is a war with the United States and its allies + Japan. A war that they would lose 100-0. So no, they would not start a war with Japan.
Compared to a war with Russia which, when won, would give them all they need. And it's actually a war they could and would win.