,
Lim Ji-yeon,
Lee Do-hyun,
Song Hye-kyo,
Yeom Hye-ran,
Jung Sung-il, writer
Kim Eun-sook and director Ahn Gil-ho.
Main •
Song Hye-kyo as Moon Dong-eun : A homeroom teacher at Semyeong Elementary School, Dong-eun was the victim of relentless bullying and physical abuse during high school at the hands of Yeon-jin and her group. Forced to drop out, she later devises an elaborate plan of revenge against those who tormented her. After resigning from her teaching position, she enrolls in an
architecture program and becomes a
chartered architect, fulfilling her dream from high school. •
Lee Do-hyun as Joo Yeo-jeong •
Shin Ye-eun as young Yeon-jin : A
weather presenter who was the ringleader of the group that bullied Dong-eun in high school. Yeon-jin conceals the truth about her daughter's paternity, passing off Ye-sol as her wealthy husband's. Responsible for numerous cruel acts, including the death of another bullying victim, her crimes are eventually exposed. She is arrested and forced to endure consequences mirroring the suffering she once inflicted. •
Yeom Hye-ran as Kang Hyeon-nam • Song Byeong-geun as young Jae-joon : The
color-blind heir to a series of luxury businesses, including a
country club,
duty-free shop,
boutique and
resort. Jae-joon was part of the group that tormented Dong-eun in high school and is the biological father of Yeon-jin's daughter, Ye-sol, whose custody he later seeks. •
Jung Sung-il as Ha Do-yeong •
Song Ji-woo as young Hye-jeong • Bae Gang-hee as young Sa-ra • Seo Woo-hyuk young Myeong-oh : A student at Sunghan High School who suffered persistent bullying and abuse at the hands of Yeon-jin's group before Dong-eun became their next target. • Jeon Soo-ah as Ahn Jung-mi : The
school nurse at Sunghan High School and the only adult who showed support for Dong-eun during her time at the school. Her concern for Dong-eun contrasts with the inaction of other faculty members. • Park Yoon-hee as Kim Jong-moon : Dong-eun's former homeroom teacher at Sunghan High School. He showed clear favoritism toward Yeon-jin's group and mistreated Dong-eun, having accepted bribes from the bullies' parents to overlook their misconduct. • Ahn So-yo as Kim Kyeong-ran • Lee Seo-young as young Kyeong-ran : A
shop assistant at a boutique owned by Jae-joon and Dong-eun's former friend. Following Dong-eun's departure from school, she became the group's next primary target of bullying.
People around Park Yeon-jin • Oh Ji-yul as Ha Ye-sol : The daughter of Yeon-jin and Ha Do-yeong, though her biological father is later revealed to be Jae-joon. Ye-sol is colorblind like her father and attends Semyeong Elementary School. Following the events of the series, Ye-sol is enrolled in a public school in the United Kingdom. •
Yoon Da-gyeong as Hong Young-ae : Yeon-jin's mother who is a devout believer in
Korean shamanism. Young-ae is complicit in her daughter's behavior and uses her wealth and connections to cover them. • Lee Hae-young as Shin Young-joon : Dong-eun's mother, who worked as a
barber. Mi-hee abandoned Dong-eun in exchange for bribes and has a long history of alcohol dependency. Her neglect and betrayal contribute significantly to Dong-eun's emotional trauma. • Heo Dong-won as Chu Jeong-ho : A teacher at Semyeong Elementary School who feels threatened by Dong-eun's hire. He is later exposed as a
child predator. • Kang Gil-woo as Kim Soo-han : Hyeon-nam's teenage daughter, who endures physical abuse alongside her mother at the hands of her father. With Dong-eun's help, she is eventually able to escape the abusive environment and pursue her education abroad in the
United States. • Ryu Seong-hyun as Lee Seok-jae : Hyeon-nam's husband, who is physically abusive toward his wife and daughter. He struggles with
gambling addiction and alcoholism, being the sole cause of the family's suffering.
People around Joo Yeo-jeong •
Kim Jung-young as Park Sang-im : Yeo-jeong's mother and the current director of Seoul Joo General Hospital. • Cho Min-wook as Kim Jong-heon : Yeo-jeong's senior during his time at the hospital. • Choi Kwang-il as Joo Sung-hak : Yeo-jeong's father, formerly the chief director of Seoul Joo General Hospital and a
surgeon by profession. Sung-hak was murdered by Yeong-cheon, a former patient, which deeply impacts Yeo-jeong and influences his involvement in Dong-eun's revenge plan.
Others •
Lee Byung-joon as Lee Gil-sung : A
pastor and Sa-ra's father. • Son Kang-kuk as Choi Dong-kyu : A
Detective Constable. • Noh Kyung (Part 2) •
Oh Min-ae as Do-yeong's mother • Kim Seon-hwa as Lee Sa-ra's mother • Jeon Jin-oh as Young-joon's subordinate
Special appearance •
Hwang Kwang-hee as radio show host •
Lee Moo-saeng as Kang Yeong-cheon : A patient who murdered Yeo-jeong's father. •
Lee Joong-ok as Tae-wook : Hye-jeong's lover. • Kim Seung-hwa as Hye-jeong's junior ==Episodes==