Renton, a young man born to scientists, and Eureka, a girl who cannot withstand sunlight, grew up together and developed a strong bond. Sadly, one day Eureka was taken away, and Renton felt helpless. Determined to rescue her, he joined the military and was soon assigned to the First Mobile Forces' Independent Youths Unit 303 due to his extraordinary skills piloting Nirvash, a bio-mechanical armor and control system. What Renton did not know was that a plan was being hatched to eradicate an ongoing alien invasion, and he and Eureka were central to it.