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.

Yuma's Neighbor identity revealed, the Tamakoma branch safeguards Yuma, Osamu and Chika by recruiting them to their group of powerhouses and eccentrics. But Border headquarters wants Yuma’s Black Trigger badly enough to send agents from its top three squads to steal it!