Zero no Tsukaima's story follows the life of the female protagonist named Louise who attends an academy for those who can use magic as a second year student. In this world, those who can use magic are either a mage or a noble. Everyone else is a commoner and is not treated equally. She is unskilled at the craft, which means she can never use her magic the way she wants to and has been dubbed the name "Louise the Zero", due to her current success rate almost always being zero. Early in the school year, the second year students get to summon their familiars; this is considered a special day where a mage summons their eternal protector and partner, which usually is some sort of creature. Louise manages to summon a human male named Saito Hiraga from Earth, leaving Louise totally humiliated. She treats Saito as any other creature, making him sleep on the floor and eat leftovers, and beats him with a whip, among other things. One day Saito challenges a noble who disrespects commoners to a duel. Saito is beaten badly at first, but once a sword was put in Saito's hands, he gained amazing powers and wields the sword with great ability. Louise and Saito, during the course of the story, face many mysteries and uncover unexpected truths.