Have you ever heard of a cat attending class?
Yes, this kind of thing isn't unusual in the small courtyard. Black Coal Ball isn't opposed to attending class; it can't go to school with a backpack like Luo Yirui, so it has to stay in the small courtyard.
It also has a deskmate, which is Jing Changle.
Jing Changle didn't go to school because he doesn't have the basic foundation. He knows simple arithmetic and some characters, but at his age, he should be in the second grade, yet he hasn't even encountered first-grade knowledge.
Both Jing Changle and Black Coal Ball are attending class formally for the first time, and the teaching methods for one human and one cat are, of course, completely different.
Black Coal Ball aims to understand human society and to understand itself.
As for Jing Changle, all the textbooks needed for first grade are piled up in front of him.
