
The thing that annoys me the most about this is the whole "he's not being a jerk, he was just hurt before" crap. A bad past may be the reason why you have the impulse to do something but it does not excuse you from acting on that impulse. I've been yelled at by customers at work before but that wouldn't excuse me running them over with a car even if it would explain the thought coming into my mind.

I find it odd that her very first assumption is that he's a prostitute. I mean for all she knows it could have been an older relative that's giving him money to help him get through university. Also wouldn't it have been easier to just show ID to prove that he's only 20 instead of punching a guy? Oh, and everyone in that school who believes the rumour sucks.
If a story is going to have violence this is how it should be. It was called out as horrible and treated properly as abuse. In my opinion this is the only good reason to have violent acts in manga like this. Also as someone who was compared to my more outgoing sibling the entire time I was growing up I got some tears flowing because I totally get thinking that it would be better to disappear than continue to be compared.