Divorced from her husband, Chiaki is single-handedly raising her only son, Junpei. Now that Junpei has grown up, Chiaki is proud of her obedient son, who sees a lot of places where he can't study. One day, Chiaki finds a test answer with "12 points" written on it in Junpei's trash can. Chiaki immediately questioned Junpei, but her trivial remarks led to a big fight. A week has passed since that day...they still haven't heard from each other...
