Crow

A girl named Sakuraba Aeris appears suddenly and rescues Karasuma Crow from a black monster at his school. These creatures, known as Ravens, target individuals with high levels of "flaps," a type of aura-like energy. Aeris is a "Luke," capable of solidifying her flaps into a weapon to fight Ravens. Crow damages the item Aeris uses to transform, but discovers that his own aura has a similar function. With his help, Aeris can still fight Ravens effectively. To stay safe from these creatures, the two must remain close, leading to Aeris moving in with Crow.