Destroy thy Neighbor! A gate to another dimension has burst open, and invincible monsters called Neighbors invade Earth. Osamu Mikumo may not be the best among the elite warriors who co-opt other-dimensional technology to fight back, 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.