Just the other day, she entered a registry marriage with a man who had a child. Her stepdaughter, Mirina-chan, was such an obedient and good girl that she seemed too good for her, and she should have been living a peaceful life in a happy family. Then, one day, Mirina-chan suddenly brought her male friends from school home. And she began ordering them to attack her. She desperately begged Mirina-chan for help, but she just watched the protagonist being raped, smiling scornfully. And from that day on, her days of being gangbanged by her daughter's classmates began.