Japan would be friendly ,and makes alliance with any country that destroy few of its cities with nuclear bomb.
Works like charm : )
I am sure Chine read the history books as well about "how to make alliances".
Well, you also have to keep in mind that allies, in today's world, is NOT necessarily an asset. I depends on your strategic vision and goal.
The USA strives to remain a global hegemony. This is a goal in which it would be worth while to invest in securing Japan as an ally/underling. But for China, it is not necessary.
First because China is NOT stupid enough to have such a goal, because China is neither culturally nor geographically suited to be a Maritime Power/Superpower. A Maritime Power/Superpower's role is best served by an "island" nation that can concentrate their resources in intervening, dividing and feeding-off from the World Island via the sea. China is huge part of the World Island, doing such would be disconcerting and counter productive.
Secondly, because today's world is already globalized. Allies are become more and more a liability than asset. Allies are great during the Cold War and before, because there are no such unified global market beforehand. But since today's world is globalized, you don't need to befriend or conquer an country to make it an ally, in order to form an economic block with them. For example, most of Today's nations could use their own trade relations and volume as a deterrence or a lure to prevent another country from seriously harming their own core national interests.
In today's world, if Japan breaks her alliance with the USA, it would actually be a bad news for China. First because this would mean that Japan would need to re-arm in order to protect herself, thus this would complicate the regional balance of power. Secondly, it is because this would mean that Japan will need to look for new allies to strengthen her own security, and such an ally will need to be close and powerful enough to be relevant to regional power balance in North East Asia. And here is the rub:
1. If Japan pick any major nation other than China as an ally, it would immediately be seen as an encirclement of China by China. Thus this will increase regional confrontation. The worst of such candidate would be Russia. Imagine a Russia-Japanese alliance, this will almost immediately force China and USA (and even the EU) into an temporary alliance, and since the US is far away, Russian-Japanese alliance will almost certainly focus on finishing off China first, before moving on to the USA. This would be very troublesome for China, because China's frontiers would be hot battle grounds. And the USA will simply seize the chance to turn China into a meat grinder to neutralize Russia and Japan. Thus ending up with China, Russia and Japan all spend their resources to destroy each other, and turn into ruins.
2. If Japan decide to be the boss of her own alliance system, she will most likely took small regional challenger nations and rogue nations to be her ally: North Korea, Vietnam, Indonesia, etc. This would mean little to no harm to the USA, EU, and Russia, but it would be a great annoyance to China. China and Japan will enter into a Cold War and competing for regional small nations to join their block against the other. None of these nations are strong enough to challenge China by themselves, they also can not really challenge China in a real war as a group, but if they decide to just walk the thin line between total hot confrontation and warm relations, and use wolf pack guerilla tactic to wear China down, it would be endless trouble for China.
3. if Japan decide to pick China as an ally, this would also be trouble for China. Because this will alarm Russia and the USA. A Russia-USA alliance, will certainly force EU in. And US-EU-Russia alliance will outclass China-Japan alliance. The only way China-Japan alliance can survive is to strike first and capture Siberia, India, SE Asia and Central Asia before the other side are prepared. Such an alliance will racially split up Caucasians and East Asians, and will spell doom for Human civilization.
Therefore, I would only wish that Japan remain within the US sphere of protection for the a few decades more. This would be the best for China and for the world.