Siryeonjungimnida

When Min Gun Lee is rejected after confessing to the upperclassman he likes, he is shocked when his crush's scary twin brother Jo Gan immediately asks him out afterward... and refuses to take no for an answer! With the nickname "Mad Dog" and a reputation for putting a teacher in the hospital, Jo Gan is the very picture of a juvenile delinquent - the exact opposite of his princely, model student brother Jo Han. Will timid Min Gun survive being in a relationship with someone the entire school is terrified of, or will his new boyfriend manage to win his heart with his rough but sincere affection? And how will Jo Han react to the situation? (Source: Anime-Planet)