You'd be surprised to find out in other mangas, and even in real life they can do far worse. An example is the kids in Bakaudon's manga. Also that edgy manga Rurokunin. In real life, I've seen some cases of violent bullying where the child is sent to the hospital. Some are accidents and some they either don't have the capacity to recognize the severity of their actions or they're just doing it because they're young and can still get away with it, protected by the juvenile laws. There are even reports of rape cases but luckily, I don't know of one that I've seen.Does kids really go that far in bullying?