While I think the author has a pretty good idea on how to write character arcs and stuff, she is pretty heavy handed with her narration. It often goes a bit too far, a bit too unbelievable in some way or another. It really is difficult to believe that someone would bully you because your father killed your mother, I also have no reason to believe that these kinds of things are common in Japan.
I feel like people like to jump to conclusion about Japan and its culture after having read a couple of manga where some fictional characters are cartoonish bullies.