Hiroshi and Yuka have been in love for a while, and he often visits her house. Eri is Yuka's mother, she raised Yuka alone since she was a child. Because she is a single mother, it has been a long time since Eri had sex. Seeing her daughter happy with her boyfriend makes her jealous. Hiroshi has worked as a porter since he was a student, giving him a strong body. Eri was attracted to his body so she did something extremely wrong... That was seducing her daughter's boyfriend! Hiroshi also secretly admired Eri's body, so when she seduced him, he quickly agreed and their wrong relationship began...