In a World where young witches and wizards train at the Tristain Academy of Magic. One of these students is Louise, who's so terrible at magic she's earned the nickname "Zero". When the time comes for students to summon their familiars, she ends up summoning Saito Hiraga, a normal teenager from modern Japan. Even though he's being treated like a dog and forced to do menial labor, Saito stays to protect his mistress. This means dealing with incoming advances from other women around him and getting involved in a war between Tristain's neighboring countries....