For centuries, the Quartz Kingdom has basked in the warm glow of the Goddess's light. That all changes one day when Demons attack the capital, laying low countless Celes. Yet even as the kingdom teeters on the brink of disaster, a black-winged orphan named Blue awakens to a terrible new power within her and vanquishes the Demons.

As the dust settles on the ravaged city and Blue comes back to herself, she swears an oath of fealty to the noble Prince Cassian. She then enters Helios Training Academy to fulfill her lifelong dream of becoming an Angel and defending the kingdom. Will Blue finally find the light she has been searching for...or an even deeper darkness within herself?