With her husband away on a work assignment and her son busy with exam season, she finds herself alone at home. To fill the loneliness, she spends her days masturbating. Her son's friend accidentally discovers her in the act and becomes intensely aroused, ultimately raping her. Another friend witnesses the scene and grows curious, soon pressuring Hisayo as well. Hidden from her son's sight, she is tormented with toys by the young men, forced to endure in silence. While her son is away, she gets caught up in orgies with these young men, and before long, she herself becomes addicted to the pleasure.