After successfully repelling Aftokrator"s assault, the Border Defense Agency is now planning an expedition into the Neighbor's realm. Yet, as in prior reconnaissance missions, only A‑class units can reliably earn a slot. With the B‑rank conflicts ongoing, Osamu Mikumo and the rest of Tamakoma‑2 race to rise in rank, hoping for a promotion before the mission launches.
At the same time, another Neighbor vessel is heading toward Border Headquarters. Observing that the assailants are aiming at the Border Expedition Vessel, troops are quickly dispatched to counter them. Yet, because fewer teams remain due to the ongoing rank battles, the organization is thrown into chaos. This fresh attack from the Neighbors casts doubt over the crucial expedition vessel"s fate.
