I am well versed in the atrocities that the Japanese committed, But that doesn't mean that you guys should be teaching so much hate to your kids that they end up doing stupid stuff like this.
Other parts of the world have experienced 10x worse atrocities but even they don't go to such extents.
You know what the problem is?
Ego
Chinese and Koreans think they are the master human race and that all other people are barbarians, so when the 倭 (wa, pejorative meaning dwarf or short) Japanese gave you people a bloody nose your ego was shattered.
And like they say, you body heals but your ego is wounded forever.
The solution to all this hate is for Japan to genuinely apologies and Chines and Koreans to let go of their ego.
You are right that there is a big element of a battle of ego in this. But you get it wrong in the direction it is going.
Most Chinese is actually unshakably confident in the superiority of their culture and is therefore more magnanimous towards the Japanese. China is a lot bigger than Japan, it is to China advantage if she can bring Japan into China led East Asian union. That is why for the past forty years China has always try to emphasize friendship, putting aside divisive issue and has invest lots of money and effort in setting up program after program of youth, municipal administrative and cultural exchange.
It is the Japanese who due to their inferiority complex that feels the needs to snub China.
Think about it, there are absolutely no meaningful advantage and purpose to what the Japanese did to anger the Chinese and Korean. These are just act of childish sticking up middle finger to you neighbors. Neighbors that really would have prefer to move on. They did it on purpose. The Japanese politician/government even stoop so low as to use such emotionally explosive issue as a political and diplomatic tools.
It is not China and Korean that want to re-open the hurtful wound, it is the Japanese that repeatedly rub salt into old wound in order to assuage their wounded ego. Haven't you noticed that the longer the Japanese economic is in the slump, the more popular the right wing becomes.
It is very easy for Japan to fix the situation, the ball has always been in the Japanese court. Japan do not even have to apologize, Japan only has to maintain the status quo and do not do things that hurt the feeling of their neighbor and let history take its course.
That is not too much to ask, is it? But it look like the Japanese simply is not courageous enough to face up to the ghost of the past and move on. And I expect the situation to get worse not better. They look incredibly more and more like Germany at the period after defeat of world war one (to be fair, Germany was very harshly treated but you cannot say the same for Japan). Unwilling/unconvinced to admit defeat to their neighbors.
Remember, Germany learned the error of their way only after they were defeated twice. After millions that had suffered an unnatural death.