Yui is a wealthy female student whose father is the president of a top company. Because her father is always working, she lives almost every day alone, but behind her good-student face, she harbors a masochistic desire to be assaulted by a man. One day, she is seen masturbating by a delivery man named Nakata, who blackmails her into having sex with him. Since then, she has become Nakata's sex slave and is trained in lewd acts...