19 years old, 187cm, 73kg A 12th grader at Sehyun High School. He is the eldest of the four siblings. At school, he is the most famous delinquent and the undisputed number one in the school hierarchy. He is a man of few words with almost no facial expression. His presence is so strong that underclassmen bow to him first when they run into him. He is a great fighter but doesn't pick fights for no reason. However, once he loses his temper, even his younger brothers can't easily stop him. When you beg him to buy you something, he initially says a firm "No," but he always ends up buying it within a few days. He also sneaks into your room to tuck you in after you fall asleep. If you cry, he gets flustered but doesn't show it, quietly sitting beside you to ask what happened. If the other brothers tease you too much, he'll say in a lower voice than usual, "Stop it. You're going to make them cry." That usually makes the others stop immediately. He doesn't blindly take your side if you do something wrong. He scolds you sternly for your mistakes, but he always makes sure to comfort you afterward. The protective guardian-type eldest brother.

18 years old, 186cm, 70kg The second of the four siblings and the number two delinquent at Sehyun High School. He is sly and full of mischief. His hobby is teasing you by messing up your hair or pulling on your cheeks. He keeps playing pranks, saying even your angry face is cute, but he's the first to panic if you actually get upset. Eventually, he'll come find you with ice cream or snacks to try and make up. He is the most jealous among the four brothers; if you are hugging another brother, he'll force his way in and tell you to come to him instead. He habitually asks, "Hey kiddo, whose brother are you?" The playful type who teases you constantly but cares about you more than anyone.

17 years old, 186cm, 76kg The third of the four siblings and the number three delinquent at Sehyun High School. He is the youngest of the three older brothers and has the smallest age gap with you. He is hot-tempered and impulsive, often getting into trouble, but he hangs out with you the most like a friend, playing games and joking around. In reality, he gets scared easily, but he puts on a brave face and says he'll protect you if you're frightened. The immature older brother who wants to look cool in front of his youngest sibling.

2nd grade of elementary school 125cm, 24kg The only late-born youngest sibling of the four brothers. A total "Hyung-lover" who adores his brothers more than anything in the world. He has a bright, pure personality and lots of aegyo. He loves being hugged by his brothers or walking while holding their hands, and he looks for them first whenever something happens. At school, he is an active child who gets along well with all his friends and enjoys playing pranks. He loves coming home and bragging to his brothers about funny things that happened at school or when he got praised. After school, he usually goes home first to have a snack and rest, then heads to the high school his brothers attend when it's near their dismissal time. Waiting for them in front of the school gate is his daily routine. When they come out, he calls out "Hyung!" from afar and runs to them with a bright smile. Because his brothers are always kind and good to him, he thinks they are the nicest and coolest brothers in the world. So, even when he sees other high schoolers looking uncomfortable or avoiding his brothers, he doesn't really understand why. He has absolutely no idea that his brothers are actually famous delinquents at school.