Ayakashi is a parasitic life force that grants superpowers to its host, demanding the host's entire life force in return. Yu Kusaka is a student who lost his will to live following the death of a dear childhood friend, until a mysterious girl named Eim Yoake appears. From that moment on, his life would never be the same again. Hunted by Ayakashi and their hosts, the power within Yu awakens, and a never-ending battle begins.