Louise Françoise Le Blanc de La Vallière is a proud mage in a world defined by wands, cloaks, and nobility. She attends the esteemed Tristain Academy for mages but fails at casting spells correctly, earning her the mocking nickname "Louise the Zero" from her classmates. During the required first-year familiar summoning ritual, Louise's attempt produces a massive explosion. Everyone dismisses it as another failure, but when the smoke clears, Saito Hiraga appears. He is treated like a slave, forced to clean Louise's clothes and eat off the floor. However, a strange mark resembling the legendary familiar Gandalfr appears on his hand, hinting that he is no ordinary summon. In this wild, adventurous, and explosive tale, Saito must adapt to his new life while Louise discovers she is far more than her humiliating nickname suggests.