Thought I'd pop in to give a bit more light on the China-Japan thing. Like most historical and political matters, it's generally not a case of one side is evil and the other is good. I want to say this won't be everything, as 5000 years of sitting next to each other and poking each other with sticks is a lot, and whilst I am getting a degree in this, I certainly don't know everything.
The current situation in East Asia can be viewed as worrisome.
Historically, China was once the world power of the East. It loomed large and strong, and the surrounding countries were either influenced into having very similar values, or simply paid tribute to them. Think of it similar to the US of A today. American culture is a large import now, and Chinese culture then. That's why East Asian countries have similar values, remants of Chinese characters in language and speech, and so on.
China saw itself as the rightful adopter of all of the world, and especially that of East Asia. A similar mindset to that of Ancient Rome; all is lesser than Rome, and for the glory of Rome, all shall eventually be conquered. China has always regarded any country especially that paid tribute to them as Chinese; Japan was once such a country, and in the mind of the Chinese popular culture, Japan is something of an unruly child, much like Tibet or Taiwan or Hong Kong, and in the vision of China, all of these either already belong to China or should do.
Japan, however, has since moved away from China, and in a similar fashion to the English and the French and the Spanish, that proximity to each other and sovereignty and time has led to Japan moving away culturally and there has always been an undercurrent of hatred; this came to a head during World War 2.
Known as the "Rape of Nanjing", the Japanese army came onto Chinese soil and destroyed towns, killed any from men, women and children and raped all they could find before killing them; a death toll of 66 million. The mindset during this time was that the Japanese were an advanced race, and that treating their prisoners like this was fine as they were animals and not really human (similar treatment was given to Western PoW). Eventually the Chinese managed to fight back, but in the West, this event is barely taught. In China, this wound is felt fresh; a similar mindset as American media portrays 9/11 is felt.
It hasn't helped that Japan has never apologised publicly for these events either.
After losing World War II, Japan was placed under American protection, and was effectively forbidden to ever have an army; in exchange and protection, it was placed under American protection. Fast forward to more modern times.
China has now grown to the second largest economy, a fifth of the world's population and has over 40 years of the Communist Party controlling all media. However, there are a large amount of problems; pollution, corruption, wealth disparity. These are things it is forbidden to try and change (very simplified, but I'm already writing an essay). It sees itself as a world power; rivalling America. It's people believe that China is Rising, to borrow that phrase from Battlefield. Now, you can try to complain about the government. And be "invited to tea" for "spreading rumours".
But the Chinese government has been using foreign powers as a scapegoat for many years now. Pollution? The foreigners want us to make things and don't care if we are poisoned. Wealth problems? China is a developing country and these rumours are foreign media trying to create chaos and disruption. President Xi JinPing has even given a speech saying that "China mustn't allow foreign ideas to encroach onto Chinese sovereignty." Chinese people are taught from a young age that China is a golden land facing evil from any and everyone who is not Chinese, victimised to know that every other country is gunning for China, and lands that belong to China have been stolen. Anyone who is pro-"Foreign" is a traitor. According to one person I spoke to, she was convinced that America would give a shot to anyone returning to China to make them stupid in case they work for the American government. This wasn't a stupid person. She was highly educated, went to a British uni, and yet had no trouble believing this. The level of indoctrination is impresssive, if worrying.
You may all remember the recent event of the island near Japan which Japan bought from an American business man and there was something of a brouhaha. And by that, the Chinese media whipped up the Chinese into riots against the Chinese and anything remotely Japanese was destroyed. To China, despite legally belong to Japan, those islands were Chinese and the Japanese had no right to them. And now, China has increased it's air space to cover a large amount of sea, including sea that belonged to Japan, Korea, Phillipines and 7 other countries without consultation from any international body or those countries. This has caused a few feathers to be ruffled in those 10 countries. China has explicitly stated that anyone caught flying in those places would be shot down. Japan and the rest refused to acknowledge China's claim, so they flew anyway.
On the borders of the seas, both China, Japan, Korea and such are all "practising" military exercises in sight of each other's territory. When the Phillipines was damaged, China initially offered "£10,000" before increasing it to £1 million due to international pressure, as China felt slighted when Chinese citizens were murdered on Phillipine soil.
In Japan, however, the new President Abe has been shown to be a supporter of the old Japanese ways. Japan, like China, has always seen itself as the King of Asia, and has always eyed other countries with the view to conquer them as well. He has spoken of "standing up" to China, and has given several very provocative speeches towards the Chinese people. He is rebuilding an army. He has recently gone to a shrine built to war heroes; those same war heroes who killed 66 million Chinese people. Japan, as I have said, has never apologised to China, and probably never will.
Other countries have gotten involved; Cameron visited to try and improve relations with China, but didn't even get involved in that kind of stuff. The other East Asian countries have basically sided with Japan in this. America sent Biden over to China, which was both a smart and stupid move. China and America also have their issues (and I won't get into them because this post is long enough), but America disrespected China by sending Biden, not Obama. However, in the current international mindset, China believes itself to be the most powerful, and is, like Japan, building a large military but unlike Japan, also has a near fantastical grip on the mindset of it's populace. So America did need to show China that there is someone much bigger ready to take it down (while America has set-backs, it does also have the best equipped and trained military, and a culture which nearly supports that military to the same extent as China).
And by focusing the rage of the people internationally, they are more likely to forget about the numerous problems at home.
So, to summarise, China and Japan has always been at each others throats. Recently, they have both gotten leaders who are very nationalistic, and have reignited those old Imperialistic tendencies. China has recently begun heavily focusing on becoming anti-foreign, and Japan has focused on becoming anti-Chinese (while a little anti-foreign thrown in as well). China has made some very internationally unpopular and inflammatory actions, and Japan has done very insulting media stunts against China. America has thrown it's weight in there as well against China, and not very politely either. It's a powder keg of egos, history and media manipulation.
I hope this was somewhat interesting as a brief introduction into East Asian International Politics.
