At Tristein Academy, Louise is a magician whose struggles with magic have earned her the nickname "Zero Louise." As an upcoming exam approaches, Louise must summon a familiar for assistance in her magical pursuits. Despite her desire for an extraordinary familiar to impress her peers, she ends up summoning Hiraga Saito, an ordinary Japanese guy. While they initially dislike each other, circumstances force them to live together, as Louise cannot attempt another summoning and Saito is stranded in a foreign land. This marks the beginning of their tale, as portrayed in Noboru Yamaguchi's novel.