The 'military enterprise RF9 (referred to as the Original Sin Army)' with super capital capabilities and the 'World United Defense Force WGF (referred to as the Defense Force)' together have the most powerful military organizations in the world.
The Original Sin Army secretly carried out many secret projects such as human enhancement projects, human weapons projects, superpower projects, and biochemical projects. The biochemical virus project is also nearing completion.
The Guards learned that there was a secret base of the Original Sin Army in Afghanistan. After confirming the news that an unknown mountain village was the original sin army's secret project research site, they conducted a raid and discovered a number of secret projects in the base. During the battle with the Original Sin Army, an accident occurred and an explosion occurred. The secret laboratory was infected with a biochemical virus, and all living organisms infected by the biochemical virus became mutants.
The leader of the Original Sin Army disappeared. Soon after, mutants appeared in the secret bases of the Original Sin Army all over the world. At the same time, the worldwide battle between the Original Sin Army and the Guardian Army also began.