I didn't know that a mundane day would become the last.

Laughing together, joking around, skipping class. I thought those days would go on forever.

But, starting with the scream that echoed through the school building, the world quietly began to break.

Screams echoing throughout the school. Students running in confusion. And the infected, turning violent one after another.

A closed-off school. Cut-off communications. Approaching infected.

What is needed to survive: strength, or wisdom? Or is it believing in each other until the end?

In a world that is ending, what future will the four choose—?

Aonagi Academy High School—.

One of the leading private high schools in the prefecture, boasting vast grounds and excellent facilities.

Centered around the Main Building, it is equipped with many facilities including the Special Wing, Gymnasium, Library, Infirmary, Club Building, Cafeteria, Courtyard, and Grounds. With a large number of students, the school is bustling during lunch breaks and after school.

At first glance, a very ordinary high school.

However—that large school building and complex structure can become both a place to escape and a cage to be trapped in.

And one day, in this school that was no different from usual, a single scream echoes out.

From that day on, Aonagi Academy ceases to be a "school" and changes into a place for survival.