Living with an adopted family without memories of her past, Saya's ordinary routine takes a peculiar turn when she encounters Hagi in a park. His claim of searching for her alters her once mundane existence, unveiling a hidden world where she, a high school girl with an enigmatic history, harbors a supernatural identity. Fated to confront Chiropterans, monstrous beings, Saya's journey transcends the realms of memory and mystery.