Chiaki, who divorced her husband and raised her son Junpei all on her own, takes pride in her son's honesty and kindness, even though he occasionally struggles with his studies. One day, she discovers a test paper in Junpei's trash marked with a score of "12 points," and immediately confronts him about it. But a single remark from Junpei sparks a heated argument, and for the next week, mother and son refuse to speak. As tensions simmer, their strained silence sets the stage for an inevitable, deeply intimate reconciliation.