To Hyun-sook and her older daughter Man-ji (Go Ah-sung), Cheon-ji was the sweet child of the family who rarely complained and studied hard, while always trying to comfort her hardworking, often-weary mother.

Flashbacks of Cheon-ji's past show that she had been the victim of cruel acts of bullying at her middle school, led by Hwa-yeon (Kim Yoo-jung), the prettiest and most popular girl in class whose true callous and manipulative nature hides a tortured soul.

[10][11] Luke Ryan Baldock of The Hollywood News called it "the best film of the year so far," with "the best exploration of bullying ever seen on-screen, as well as being an uplifting tale of life after death and the importance of understanding."

He also praised the script as "brave" for "[tackling] such complex issues in a fair, balanced, and non-judgmental way," and the acting as "miraculous across the board, with the young cast taking centre stage and representing the full gamut of emotions.

"[12] Describing it as a "superbly constructed drama," Richard Kuipers of Variety wrote, "Rarely, if ever, has the topic of teenage bullying been examined in such forensic detail and delivered with such devastating emotional impact," and that "helmer Lee Han maintains perfect tonal control and elicits fine performances from a predominantly female cast.