In the 26th century, humanity faces extinction due to a rapidly deteriorating environment and overpopulation. To combat this, the United Nations initiates the Terraformars Project, aiming to terraform Mars by introducing moss and cockroaches, organisms capable of surviving harsh conditions. Over 500 years later, the moss has transformed Mars into a habitable environment, but the cockroaches have evolved into humanoid creatures known as Terraformars, possessing immense strength, intelligence, and a hostile disposition toward humans.

The story begins with the Annex I mission, where a crew of 100 genetically enhanced humans is sent to Mars to exterminate the Terraformars and retrieve samples of the moss. Each crew member is modified with the DNA of various organisms, granting them unique abilities to combat the Terraformars. However, the mission quickly turns disastrous as the crew is overwhelmed by the Terraformars' ferocity and adaptability. The survivors, including Akari Hizamaru and Michelle K. Davis, struggle to complete their objectives while uncovering the dark truths behind the mission and the unethical experiments conducted on the crew.

As the narrative progresses, the focus shifts to the Annex II mission, which involves a larger and more diverse team of genetically enhanced individuals. This mission delves deeper into the mysteries surrounding the Terraformars and the true intentions of the organizations funding the expeditions. Key characters such as Shokichi Komachi, Eva Frost, and Adolf Reinhard play pivotal roles in the unfolding conflict, each driven by personal motivations and grappling with the moral implications of their actions.

The series explores themes of survival, evolution, and the consequences of humanity's interference with nature. It also examines the ethical dilemmas of genetic engineering and the exploitation of individuals for scientific advancement. The Terraformars themselves are portrayed as both antagonists and victims, their evolution a direct result of human intervention. The narrative is marked by intense action sequences, strategic battles, and a high-stakes atmosphere as the characters confront the ever-present threat of the Terraformars and the hidden agendas of those in power.