A boy falls to his death at school, but Ok Chan-mi does not believe that her twin brother, Park Won-seok, committed suicide. Chan-mi transfers to her brother's school, Yongtan High, and meets Ji Soo-heon, who witnessed her brother's death. A "hero," who avenges bullied students, appears at Yongtan High. Chan-mi speculates that it may be connected to her brother and starts looking for this hero.
as Ok Chan-mi
as Ji Soo-heon
as Seok Jae-beom
as Ki Oh-seong
as Gook Ji-hyun
as Tae So-yeon
as Jin So-jeong
as Hong Ah-jung
as Sa Joong-kyung
as Lim Seung-woo
as Ma Nak Joon
as Park Won Seok / Ok Chan Kyu
as Hwang Soo-na
as Gu Ja Taek [Yongtan High School's Teacher]
as Park Na-rim
