Sadly, bullying is a big issue in Korea.
Bullying is incredibly high there, but most just accept it as commonplace. Many adults even have a mentality that it's helping to raise the kids up to understand the struggles of life. Or, they just don't know how to help.
One video that gives a good idea about it is a Youtube video by Simon and Martina (formerly Eat Your Kimchi). They were Canadians that moved to Korea initially as teachers (they've since moved to Japan). They saw bullying happening first hand. Video's from 2012 though. To find it, search "Bullying in South Korea Simon and Martina."
I feel so bad for MCs in Korean webcomics.. So many shitty things happen to them just for the sake of a plot. Authors seem to have a bit of a sadistic streak, don't they?
On the side note, there is so much bullying (and social outcasting) done in these webcomics, that it make me wonder if bullying is so rampant and extreme in South Korea.