Weeks after the dust settles from Sosai X's destruction, a tiny fragment of the alien revives and begins to rebuild itself into Sosai Zed. Using the remains of an old shipyard, Zed builds a vast mechanical pyramid fortress and levitates it over the ocean. Meanwhile, the rest of the world quits rebuilding from the wreckage of the thwarted Solar Shift Plan and go back to what they do best: waging war. We meet Count Egobossler, successful ruler of a growing number of territories, and an aspiring megalomaniac. Egobossler meets Sosai Zed, who decides to use Egobossler's brilliant military tactics to his own advantage, and the two strike a deal. In the wake of Chief Anderson's death in Gatchaman II, Nambu is promoted to Chief Administrator of the ISO. The Kagaku Ninjatai cope with the unusual peace. Feeling useless during peacetime, Joe wallows in boredom and self pity while Nambu tries to find a way to recharge him after his near-destruction in G-II.