Kazuto Ishikawa is a first-class architect. He is married to Kiyomi. They have a son, Tadashi, who attends high school and a daughter, Miyabi, who attends middle school. They live together in a refined home, designed by Kazuto. An injury causes Tadashi to quit playing soccer. Since that time, Tadashi often stays out all night without permission. One evening, Tadashi leaves home and does not return. Kazuto and Kiyomi become worried about their son and consider going to the police. News then reveals the murder of Tadashi's classmate. The police suspect that Tadashi might be involved in the murder.

Half a Confession introduces itself as a thriller and abruptly changes gears, transforming into a tale of morality with deeper insights into its characters than we had anticipated. It begins when Soichiro Kaji (Terao), a retired detective, walks into police headquarters and confesses to the murder of his wife. We learn that the victim had prematurely developed Alzheimer's after the tragic death of their son, and in her suffering, had asked to die. The police chiefs would be far more content to take him at his word if it were not for a conspicuous hole in his story: 48-hour gap between the alleged murder and his confession. Fearing a public relations nightmare, they are eager to bury the incident and keep the press in the dark.

A community is shocked when the bodies of an elderly man and the manager of a home-visit nursing centre are found. The passing of 42 elderly patients is connected to Shiba, a caretaker recognised for his affection and dedication.

A popular high school student, who is good at sports and studies, must suppress kissing for 24 hours.