Luhan happens to be the most famous at his school. Good looks, good grades, rich, and kind. It's all you could ask for. All the girls want him, and guys envy him, but still stick close by to him wanting a good rep. 
Minseok is someone no one wants to be around. He seems like an overall gloomy person, but no one ever takes the time to talk to him. He's bullied by most of the boys, and sometimes the girls even. 
Luhan happens to have a crush on Minseok, more like he has had this crush for more than 3 years. After a long time, Luhan finally gets to talk to Minseok.