Seven Days War

Mamoru Suzuhara is an introverted high school student who spends his free time reading up on modern warfare. Upon discovering that his crush, Aya Chiyono, is reluctantly moving away with her family next week, he musters enough courage to ask her to run away with him. Consequently, Mamoru, Aya, and four of their fellow classmates set out and camp in the abandoned Satomi Coal Factory. After enjoying themselves during their first day there, they come to the surprising conclusion that they may not be alone in the factory.