Chie has raised her son Shou alone since he was a child. Devoted to caring for her frail son, she tirelessly manages housework and her job, always putting her own needs aside. However, Shou refuses to attend school and spends his days cooped up in his room with his friend Takayuki. One day, Shou's homeroom teacher, Nakaya, visits Chie out of concern for Shou. Burdened with anxiety and sorrow, Chie confides in Nakaya about how Shou blamed her the previous night for not having a father, and in her emotional vulnerability, she ends up physically intimate with him. By chance, Shou witnesses the encounter, and soon Takayuki also learns the truth. This incident drastically alters the dynamics of their household, setting off a chain of irreversible events.