Follows the story of Ok Chan-mi as she seeks revenge for the death of her twin brother.

Ok Chan-mi is a 19-year-old high school student. She used to be a shooter for a high school team. One day, Ok Chan-mi's twin brother dies. She chases after the truth related to her his death. She gets involved with Ji Soo-heon. On behalf of bullied students, Ji Soo-heon takes revenge on their tormentors.

Ok Chan-Mi (Shin Ye-Eun) is a 19-year-old high school student. She used to be a shooter for a high school team. One day, Ok Chan-Mi's twin brother dies. She chases after the truth related to her his death. She gets involved with Ji Soo-Heon (Lomon). On behalf of bullied students, Ji Soo-Heon takes revenge on their tormentors.—AsianWiki

A boy falls to his death at school, but Ok Chanmi does not believe that her twin brother, Park Wonseok, committed suicide. Chanmi transfers to her brother's school, Yongtan High, and meets Ji Sooheon, who witnessed her brother's death. A "hero," who avenges bullied students, appears at Yongtan High. Chanmi speculates that it may be connected to her brother and starts looking for this hero.—Hulu

Ok Chanmi's twin, Park Wonseok, falls to his death at school. Chanmi transfers to her brother's school, Yongtan High, where she meets Ji Sooheon, a witness to her brother's death. Chanmi begins to explore the unsolved mystery of her twin brother's death.—TV Guide