Living alone with her son, Ryouko Murakami has raised Satoru as a single mother. Now that he's entered college and recently started dating a girl, she feels both relief at his growth and a deep loneliness in her heart. One evening, she prepares dinner and waits for Satoru to come home, but he doesn't return until late at night. During the long wait, anxiety consumes her—imagining him affectionately spending time with his girlfriend. Fearing she might lose the son she's nurtured so carefully over the years, she begins to consider drastic measures to reclaim his attention.