[Ruka] became Dai's new mother due to divorce. - However, [Ruka] is a studious mother, and Dai is fed up with being forced to study every day, so he consults his classmate, the evil brat Masa... - One day, Masa lies and says, ``Dai-kun forces me to cheat every day.'' - Shocked, she has no choice but to listen to what Masa has to say in order to protect her from the big trouble if the school finds out, and ends up having her big breasts fondled and even having sex with her... - Dai, who secretly photographed the evidence, blackmails his mother-in-law and takes revenge!