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.

Border headquarters is abuzz with gossip about talented new rookies Yuma and Chika. But it’s Osamu who attracts the most attention when an A-Rank agent challenges him to a duel. Then it’s Yuma’s turn to fight when another A-Rank agent challenges him! Plus there’s that meeting with Border’s top brass that they just got called to… Is there such a thing as too grand an introduction?