With Zeon losing their foothold on Earth, the 603rd is given a new project — to infiltrate a prototype weapon into the Federation airspace and attack Federation warships launching from Jaburo. Ensign Werner Holbein, an arrogant naval officer who boasts a proud maritime family tradition, is assigned to the Jotunheim to pilot the mobile diver unit Ze'Gok.

Situation for Zeon is getting desperate after the Federation successfully sieges the space fortress Solomon. Upon arriving at A Baoa Qu, Jotunheim is visited by Col. Herbert von Kuspen, a uptight high-rank commander from an elite battalion, who immediately try to assume command of the ship but meets resistance from both Monique and Prochnow.

Just as Gihren Zabi proudly announces to his troops the decimation of the Federation fleet by the Solar Ray, the 603rd received its latest prototype weapon — the massive Big-Rang mobile armor. When the Federation launches a large-scale desperate attack on A Baoa Qu from two directions, the Kuspen Combat Battalion is assigned to defend the E field, and Oliver (to his shock) is ordered to pilot the Big-Rang.