Why do Japanese people like to watch China's operas on TV? Is this the case in history? Their Chinese grammar is "greatly" wrong, can they still understand it?

Because China is very powerful in history, it can be said that it was the largest country in the world at that time. Japan naturally envies us, so it learns from us everywhere, including writing, kimono and so on. Isn't "Dragon Ball" adapted from our The Journey to the West? The computer game "The History of the Three Kingdoms" series is the same.