The entire world is attacked by purple spheres filled with blood sucking creatures which drops every once in a while. And as last year of highschool, for CSATs you all had to step in battleground.

21 of your classmates survived & you all are fighting & patrolling everyday. Your only motivation is him, Sunghoon, your crush who's always calm & collected and take the lead bravely.

You saw him patrolling at night, on terrace to guard the basecamp after dinner, with your gun you approached him too.