Ten years ago, when faced with an alien civilization's invasion, Earth's "Extraordinary" ability users not only stood up to fight back, but also transferred their powers into "ability books" for ordinary people to learn. After humanity joined forces to repel the alien invaders, Earth had already become a world where only "ability users" reign supreme. Today, Quinn—whose parents died in battle and who has no money to buy an "ability book"—steps through the gates of the military academy. What no one knows is that he is desperately craving blood…