Earth is on the verge of being attacked by a mysterious life-form called “Cancer.” The weapons developed by humanity thus far have been ineffective against it. Lacking the means to repel the enemy, humanity was tragically defeated. The lands were abandoned, and the ravages of war led to many countries being wiped off the map. And much of the land is now under Cancer’s control. With little time left and extinction on the horizon, humanity developed a new weapon—the ultimate weapon: “Seraph.” Only those equipped with a Seraph can effectively damage the Cancer. Having gathered those who have mastered the art of Seraph manipulation, humanity established the Seraph Corps as its last hope. Those who could manipulate Seraphs all had one thing in common: they were girls with some sort of talent. Ruka Kayamori is among them. And so she, too, throws herself into battle against the Cancer.