There are three countries in this world, countries C, M, and S. Country C, where the male protagonist lives, was once the most populous country in the world. In 2030, a huge meteorite hit country C, paralyzing country C. Instead of helping country C, the two countries M and S joined forces to launch a nuclear attack on country C. Country C fell and was divided between M and S. Country M almost massacred all the indigenous people in the area, and Country S took the indigenous people into the labor force. Country S was divided into three levels, the ruling class and nobles were the first class, ordinary residents were the second class, and the natives of country C were the third class. The male protagonist's father died due to resistance when country S invaded country C, and the male protagonist's sister was abducted by country M. In 2050, an economic dispute broke out between country M and country S. Because the interests of country S were not satisfied, they openly provoked a war. However, country M, under the banner of crushing the class system, added a large number of people from country S. Country M had equipment and numerical advantages, causing country S to retreat steadily. Country S has launched a new policy that allows your family to go to a safe place as long as you join the army. The male protagonist joins the army for his mother.