Shingetsu and Asahi, inseparable since childhood, grew up on a secluded island where the laughter of children was seldom heard. On the night of the summer festival, Asahi—a girl long afraid of the dark—finally gathers her courage and invites Shingetsu, the boy she grew up with, to the celebration. But when the seal of an ancient shrine is broken, an angel appears—a young maiden whose radiance lights up the night. Thus begins a fateful battle, burning with passion… with the destiny of the world hanging in the balance!