Yoon Hana / actress: Lim, Joo-Eun

A bright and righteous high school girl with exceptional Taekwondo skills. She always protects her beloved twin sister, who has a slight limp. When her sister dies, Hana gains a special ability; she can see and become possessed by ghosts. Once she becomes possessed, she exerts monstrous strength... Due to Shin Ryu's warmhearted care for Hana, she falls in love with him. However, he begins to use her possessed being to punish criminals. She begins to doubt whether she is doing the right thing.

Yoon Doona / Actress: Park Ji-Eun

Hana's younger twin sister who has a slight limp. Shy and introvert, Doona always depends on her older sister with trust. After Doona becomes killed in a fire, her ghost possesses Hana, releasing her wrath.

Shin-Ryu / Actor: Lee Seo-Jin

An incredibly gifted criminal profiler. With exceptional intuition and irresistible charisma, he immediately penetrates the minds of criminals. He lost his mother and sister in a horrifying incident at a young age, but the criminal was acquitted due to Baek Do-sik's legal defence. Since then, Shin-Ryu has been determined to revenge on vice. When he finds out about Hana's special ability, he begins to use her power to murder criminals. Soon enough, he sees an opportunity to revenge on Baek Do-sik.

Jung Si-woo / Actress: Park, gun- il

A high school student who is often bullied by his friends. He develops a crush on Hana, the only person who stands on his side and treats him nicely. He tries to stop Ryu from using Hana to kill people... Eventually, this youthful 18-year-old boy risks his life to protect Hana.