Can I go back...?

There's a girl named Seol-ah, she's the twin sister of Seventeen's S.Coups. She was originally going to debut as the only female member of Seventeen, but she got hurt by another male trainee, and that male trainee was kicked out because of that incident. Seol-ah was anxious, so she believed in the other members and held on, but when it didn't work out, she left...