Cha Hakyeon or better known as the infamous "N", is freed from the Cheongguk Juvenile Correctional Institute after being found not guilty of murdering his father. He tries to lead a normal life in the outside world, but finds that it is vastly different from life in juvenile prison. N begins to attend high school in hopes to finish his final year and graduate with a diploma. He also finds a job at the car workshop to support himself. However, he is constantly bullied in school and does not have any friends besides Se Ri. Everything that goes wrong in the school is blamed on N as well.

Kim Jongin or Kai is sent to the Cheongguk Juvenile Correctional Institute after being found guilty of two cases of murder. He was brought into the juvenile prison along with 4 other convicts which he became close with soon after. There he meets the fearsome senior resident of the juvenile prison, known as Dragon, who has the life of every other convicts in the palm of his hands. After going through numerous psychotherapy, Kai slowly starts to reflect on himself and realise that the juvenile prison isn't the place for him. He wants to be out there, pursuing his newfound dreams and pursuing the one he loves.

Cha Hakyeon (N), 21

Kim Jongin (Kai), 20

Yong Junhyung (Dragon) , 22