Strictly speaking, the later extension of the word "Japanese" is not the usual extension, because it has nothing to do with the original intention of "Japanese" and is a very special example in the evolution of Chinese characters. Now, it has entered the state of origin. I have seen such a joke: say "day". Standing days are called "old", lying days are called "Dan", men's and women's days are called "public holidays", men's and women's days are called "weekends", men's and women's days are called "days" and so on, all of which can make people laugh.
However, the later extension of the word "Japan" involves pornography after all, and can't be used as a joke casually, especially in classics. It is inevitable that Yu Xiuhua's "Japan" in "The Mountain Shades the Day" will not be accepted by everyone. I don't want to defend Yu Xiuhua. I noticed that she didn't defend everyone's criticism. I think she realized that she was wrong. Therefore, I prefer to believe that she is playing a prank.
In today's headlines, I saw that many people, especially some women who wrote poems, spared no effort to attack Yu Xiuhua, not with a critical attitude. This kind of jealousy and unkindness is the exposure of "evil" of human nature, which is far more harmful to poetry than Yu Xiuhua's influence on the color interpretation of Tang poetry.