Sachiko, a 12-year-old girl in junior high school, has a complicated life. When she was still an infant, her father disappeared. Her mother, who works in a bar, is secretive and distant. Longing for an escape from her dreary existence and lacking any kind of parental guidance, Sachiko has a short-lived affair with her sixth-grade teacher, Ogata. But fearing that his indiscretion might be discovered, Ogata moves to a town far away. Although he and Sachiko continue a written correspondence, soon the absence of her only real friend and confidant leads Sachiko into a deep melancholy. When her mother attempts to commit suicide, the turbulence of Sachiko's life becomes too much to bear. After dropping out of school, she finds temporary solace in the company of others who have fallen through the cracks of middle-class society. But when she is forced back into the confines of her classroom, her long-dormant rage begins to surface and her life quickly spins out of control.