Wow...
China is maybe ten times the size of Japan. It is probably about the size of Europe. So inveitably, distance leads to differences, and differences sometimes lead to conflict.
People in Guangzhou, for example, are very different from people in, say Beijing. They look different, have different statures, complexions, behave differently, wear different clothes and even eat different types of noodles. They speak dialects incomprehensible to each other. It's just like comparing different Europeans like French and Italians.
And the Europeans never stopped fighting amonst themselves either.
Compared to China, Japan is a small island nation. And they had been fighting amonst themselves for a VERY LONG time until the Meiji era or something where one Shogun (warlord) defeated and united the whole Japan. China was the same but because of her size, took a longer time to sort things out. The Koreans, erm... aren't they still separated after last fighting a war sixty years ago?
But China is one people and today, one nation again.
Chinese people have a long history of civilisation, science, culture and innovation and many other good values. It would take 100 times more pages to list the good things about Chinese culture than the bad things.
China, Chinese, are not perfect. Neither are the Japanese or the Koreans or any race for that matter. But I'm not here to dis other cultures.
It is unfortunate that the Chinese blood in you only gave you gluttony. What other blood run in you? Whatever it is it can't be good blood either cos it gave you ignorance, stupidity and bigottry.
Your knowledge of Asian history is pathetic and you cannot see beyond the tip of your nose. It is ironic that you are ashamed of your Chinese blood cos I'm sure most Chinese people will be very ashamed of you, too.