You thought your neighbors were bad...but at least they're not aliens trying to kill you!

Earth is under constant threat from Neighbors, invincible monsters from another dimension that destroy our way of life. At least we have the elite warriors of Border, who co-opt alien technology to fight back! Meet agent Osamu Mikumo, not the best, but along with his Neighbor friend Yuma, he'll do whatever it takes to defend life on Earth as we know it.

It's day two of the sealed environment phase of the away mission exam, and the examinees are diving into the demanding battle simulation, a strategy game that pits squad against squad! Unfortunately for Osamu and the rest of Suwa's Squad 7, their first opponent is Mizukami's Squad 9, which is already at the top of the test rankings. Does Suwa's Squad 7 have any hope of clawing its way up from last place?