Several years after the death of his father, Daichi Manatsu returns to Globe's Tanegashima base and while exploring an abandoned building where he befriended a mysterious boy called Teppei Arashi during his childhood, he is entrusted with a gun-like artifact called the "Livlaster", that allows him to pilot the "Earth Engine", a massive mecha that is mankind's trump card against the alien race Kill-T-Gang, that threatens to destroy all mankind.