one day, an unknown royal blue spherical life form suddenly appeared in the world, causing harm to humans. medium and large spheres can hurt people, and small spheres can attack people. in the case of crisis, high school students across the country received military training and were organized into military reserve troops and began to fight with guns in various regions of the country. the task of preparing soldiers is to defend and destroy small spheres deployed on the front line to move towards the city center. eee。