The Novel’s Extra (Remake)

Each novel often has its own world and many characters who live in it.
However, apart from the main characters and their assistants, as well as several other minor personalities, we know nothing about them.

"Cheundong, what level are you?"

I have no idea who I am.
I don't even know why they call me that.
My entire story may be limited to the fact of entering a specialized military school.
My line barely touches the main line, so my name is difficult to find on the pages of this novel.
I'm just out of the story... or rather, I'm just one of many sets