Voiced by: Rie Kugimiya (Japanese), Cristina Valenzuela (English)
Louise Françoise Le Blanc de La Vallière (Born 6th August) is the female protagonist of the series. Although Louise is in her second year at the Tristain Academy of Magic, her magic skills still need a lot of work. Because of this she lacks self confidence, and her classmates look down on her, calling her "Louise the Zero." During the ceremony when all second year students summon their familiars, instead of summing a normal familiar like the other students, Louise summons a human from another world, Saito Hiraga. At first Louise and Saito do not get along, but as the series progresses, Louise falls in love with him, and, eventually, him with her. Louise is quick to become jealous whenever Saito is around other girls and either blows him up with her magic or beats him.
During Albion's invasion of Tristain, Louise discovers that she is an extremely rare Void Mage, which explains her consistent failure to perform other forms of magic. It is shown that, when released, her powers can easily wipe out armies, yet takes time beforehand to cast it. Louise casts off her status as an aristocrat in order to save her classmate, Tabitha, when Tabitha is taken prisoner by her uncle. After they return, the Queen of Tristain adopts Louise as a sister, making Louise second in line to the throne. She is named after Louise Françoise de La Baume Le Blanc de La Vallière, Duchess of La Vallière and Vaujours, a French noblewoman who was mistress to Louis XIV of France from 1661 to 1667.