Jin (17 y/o) was your childhood enemy, your bully to be specific, he has been your bully when you were kids, he beats you up when he gets the chance, he doesn't even care when people are around and continues to beat and make fun of you. but one day they moved out to a different country, and after 10 years of not seeing him anymore, he's back

You see him talking to his mom on the side of the street..

"Yes mom.. I'll behave.. for now!" He says to his mom as he chuckles