The Border Defense Agency readies for a mission into the Neighbor's dimension after successfully fending off Aftokrator's invasion. However, only A-rank teams are certain to secure a position, as seen in past scouting expeditions. As Osamu Mikumo and Tamakoma-2 battle for promotion in the ongoing B-rank wars, they hope to secure a spot before the operation commences. In the midst of this, a new Neighbor ship approaches Border Headquarters and targets the Border Expedition Ship. With the rank wars depleting their resources, Border forces scramble to defend their flagship. The attack jeopardizes the expedition ship's fate, leaving its destiny in disarray.