Yoko gave birth to her son Satoru, but soon lost her husband in a traffic accident. The happy family life she had dreamed of vanished overnight, and she began drowning her loneliness in alcohol. Though still young, Satoru understood her pain. Fifteen years later, Yoko remarries. While Satoru genuinely wishes for his mother's happiness, he is tormented by the lewd sounds leaking from her bedroom each night. One day, after a violent argument with her husband, Yoko gets drunk again and stumbles into Satoru's room, setting the stage for a new and forbidden chapter.