Renton, son of scientists, and Eureka, a girl who cannot stand the sun, were raised together from a very young age and grew close. One day, Eureka is taken away. Powerless at the time, Renton vows to rescue her. He joins the military and, due to his outstanding performance with his Nirvash, a bio‑mechanical armor/control system, he is assigned to the Independent Youths Unit 303 of the First Mobile Forces. Unbeknownst to Renton, a plot is underway to quell the ongoing alien invasion, involving both him and Eureka.