In the distant future, in the year 5012, Earth faces an unexpected invasion by aliens and their creations, the Machine Lifeforms, which have brought humanity to the brink of extinction. The surviving humans have fled to the Moon as refugees and plan to use robots for a counterattack. However, the war has reached a stalemate due to the infinite reproduction of the Machine Lifeforms. In response, humans have developed a new robotic soldier. This ultimate weapon is called Yorha. Newly dispatched to Earth, 2B joins 9S, who is currently on duty there. During their mission, they encounter countless mysterious events. This is the story of the lifeless robots and their endless struggle for the human race.