Kusaka Yuu is an average high school student who lives an average life with the weight of the death of a childhood friend always on his mind. Little does he know, there is a war going on where creatures, called Ayakashi, and their users fight among each other, that is until he meets Yoake Eimu. Bearing a striking resemblance to Kusaka's childhood friend, Eimu is an Ayakashi user and her chance meeting with Kusaka, will change his life as he knows it forever.