Noriko and Kazumi arrive at the space fleet led by the space battleship Exelion. The girls get introduced to a hot shot female fighter named Jung Freud. During one of their mech training sessions, Jung spars with Kazumi, and end up in a part of the station where they discover one of the mechs of their enemy. Later on, Noriko and Kazumi are sent to partake in a special mission to investigate an object traveling at near light speed. With the laws of quantum physics and time dilation, the mission that would normally take just a few minutes will span several months. But they discover the object is the Lexion, the ship that Noriko's dad used to command.

The fleet advisor tells Captain that the aliens are going to attack Earth. Coach has been training Noriko, but Jung wants to test Noriko by challenging her to a duel. Noriko is still shaken from the death of her comrade and breaks down when they are outside. As the fleet is preparing to jump back to Earth, hoping to hide their trail in subspace, they are suddenly attacked by the aliens and everyone scrambles for their mechs. Noriko is benched for the battle. Things look bleak as most of the defense forces are wiped out, but Noriko manages to get out of her rut and moves to pilot the force's super prototype mech called Gunbuster.