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 five of the Sealed Environment Phase of the test, and the mission is to create Trion soldiers for battle simulations. The soldier-creation tools are robust, testing each squad's creativity and wits. At the bottom of the rankings, Wakamura's Squad is going to adopt a strategy concocted by none other than Hyuse!