At the Amazawa Girls Academy, Amazawa Izumi and Mashiro Aya cross paths. Izumi's father hires Aya to eliminate the "Midnight Ghost," a puzzling phantasm that causes any girl it encounters to slip into a profound slumber from which they can't wake up. Even though Aya's nonchalant demeanor irritates Izumi, will they manage to work together to overcome the challenge? Additionally, what other troublesome spirits will they encounter, and how will their partnership evolve?