In exchange for saving a beautiful blonde milf from being attacked by a pervert, the main character, Noriyuki, is taken into a love hotel.
He is about to lose his virginity! But just as he is about to do so, the woman transforms into a lamia!
The woman says: "I'm sorry, but you're going to die here".
Just as the woman was about to swallow Noriyuki whole while saying this, someone burst through the door. This someone was.... A plump milf, dressed in a frilly magical girl costume!
It was Rei, a childhood friend of his mother.
Noriyuki has sex with Rei in order to make a contract with her to protect him.
At that moment, another magical girl appeared! It was.... Noriyuki's mother, Yuki!
The battle between the evil Princess and the magical girls begins...