One day, unknown sapphire-blue spherical life suddenly appeared in the world, which brought harm to human beings. medium and large spheres can hurt people, and small balls can attack people. under the situation of crisis, high school students across the country received military training and were organized into military reservations. began to fight with guns in all parts of the country, the task of the reservists is to defend and destroy small spheres deployed at the front and moving toward the city center. It is mainly a story about high school students who become soldiers and begin to fight with guns.
