Yui was frustrated by her husband's busy work schedule and frequent absence. One day, her stepson Akira saw her masturbating in the bathroom. Akira was excited and touched the sleeping Yui, but when Yui woke up, she tried to run away. Unable to bear the Yui in her body, Yui stopped Akira and ended up having sex with him. After that, Akira would seek Yui's body at every opportunity...