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.

After being crushed in their last Rank Wars match and Jin refusing Osamu's request to join their squad, Tamakoma-2 is at a loss. Osamu is determined to learn how to fight with his team using his limited Trion and gets help from an unexpected source. But with a prediction of another invasion looming overhead, training may have to wait.