- Based on Kanae Minato's 2008 best selling novel "Kokuhaku" (has sold 700,000+ copies to date).
- After reading the novel "Kokuhaku" director Tetsuya Nakashima wanted actress Takako Matsu to play the main role. Enough so that he said if Takako Matsu would not play the role he would not have made the film.
- Filming began October 24th, 2009.
- Auditions were held for potential actors to play the students. Of which 34 were selected out of 1,000.
Yuko Moriguchi (Takako Matsu), a junior high teacher, announces she will resign. She reveals that her daughter, Manami, was killed by two pupils in her class, whom she dubs "Student A" and "Student B". Her disclosure of their behavior soon reveals their identities. She admits injecting her dead husband's HIV contaminated blood into the milk cartons that the murderers have just drunk from. The rest of the film describes the aftermath of this event in a series of first-person narratives from the two students, Moriguchi, and others.
A new enthusiastic teacher is appointed. Student A continues to attend classes but B has developed psychiatric problems. It is revealed that Student A, who planned the murder, did not actually kill Moriguchi's daughter by electrocution; instead she drowned because student B threw her into the pool.
Student B is worried that he will soon die from AIDS and refuses to clean himself, as he equated the smell of untamed hair and body odor to being alive. His mom tries to help but fails as Student B reacts violently to her gestures and shuts himself in his room. It is revealed later that Student B killed Manami on purpose, as a gesture to validate himself in the eyes of Student A, whom he considers his only friend. His mother eventually realizes that her once good and kind son has transformed into an unknown monster. Seeing no hope, she decides to end their lives, but in the ensuing struggle, she is killed by her son, who is captured by the police.
Student A describes how his mother divorced his father when he was young because she was unhappy with the role of a house wife and chose instead to pursue her scientific ambitions. He wants to prove himself to her and to earn her attention, which evolved from clever little inventions to gruesome recordings of him killing and dissecting animals. His first public invention, an electric anti-mugger wallet, earns him a science fair award but fails to make the headlines because of a sensational murder by Girl A that occurs on the same day. He decides to kill someone so that he can become front page news.
After the incident, Student A befriends Girl A when they were forced to kiss by the rest of the class as part of their escalating bullying tactics against Student A. Girl A begins to develop feelings for Student A, but is killed by him out of rage after a heated argument.
At graduation, Student A plants a bomb in the lecture hall and plans to activate it after his speech, but the bomb goes missing; he then receives a call from Moriguchi telling him she moved the bomb to his mother's office, killing her instead. Moriguchi appears at the end, and tells Student A, overcome and humiliated, that this was her revenge, and that his redemption now begins, but she adds, "just kidding", referencing to what Student A told her when he confessed that he killed her daughter.