Kazuki Shikimori is a 17-year-old student at Aoi Academy, an elite school for magicians. Each magician has a limited number of spells they can perform, and exceeding this limit will cause the user to turn into dust. Although Kazuki's magic count is below average compared to his classmates, he manages to keep it under control. One day, three girls suddenly appear before him, seeking his genes. However, their appearance may also mean Kazuki's doom as his magic count steadily decreases.