Who is Xu Gongzi Katsuji? Who knows this relationship very well?

He is definitely not simple. There are only two conjectures to tell such a fascinating story. One is that he is good at making up stories, and the other is that he has experienced these things himself, so he can tell stories so well. Then, make a big guess. From the perspective of fugue, the person who can tell such a story is Ishino, so maybe Lao Xu is like Ishino. I saw on the Internet that Lao Xu should be a master of Dan Dao, a master of ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~