Hae-sung’s homeroom teacher and a fixed-term teacher at Byungmoon High. As a child, Bong-ja was bullied but found comfort in Hae-sung, her first love—until he suddenly transferred. Hearing he badmouthed her, she vowed revenge, transforming herself into Soo-ah through intense dieting and a name change. Now a teacher at Byungmoon High, she meets a new transfer student: Jung Hae-sung. At first, she thinks it’s just a coincidence—until she realizes it’s really him. But why is he here?