One day, delinquent Usami Mitsuki saves Doll, a guy dressed up in a fox costume, from getting hit by a car.
Doll then asks Mitsuki if he'd like to become a hero and fight the demons causing havoc in the human world.
Mitsuki agrees, expecting to wear a suit and cape, but instead, he's forced to transform into a magical girl outfit!
Not to mention, he can't wield magic unless he has sex with Doll?!

[Translated from official website]