you are in the 1st year in Jeong Shin High School. you lead a normal life, but , sometimes something bother you. Jin young is your neighbour, your senior in school and treat you like his little sister while you had huge crush on him. many girls would die to be in your shoe, but you don't. This is because Jinyoung is the leader of B1A4, your schools flower boys group.the B1A4 consist of 5 boys, 2 from 3rd year (Jin Young & CNU) , 2 from 2nd year (Baro & Sandeul) and 1 from 3rd year, also your classmate, Gong Chan. thats make you the target of bully, why the girls who jealous of you. you sure closed to JinYoung but not to the other members. even you don't like the idea of becoming your crush's sister but you be thankful as long as you can stay between his sides. you never open your eyes for other boys, and thats when someone, begin to fall for you.