World Trigger is an adaptation of the 2013 Japanese manga series of the same name by Daisuke Ashihara.
In the city of Mikado, a portal to an other dimension opened four years ago. Giant, seemingly unstoppable creatures emerged, quickly known as Neighbors, and wreaked havoc on the metropolis. The use of artificial weapons in the battle with the aliens had essentially no impact. When all hope appeared lost, however, a band of enigmatic warriors showed up and defeated the creatures by employing unidentified technology. The group quickly founded the Border organization, which has since been devoted to researching and combating this new threat.
Osamu Mikumo, a student in middle school, conceals from his peers that he works as a recruit for Border. However, as Yuuma Kuga, a new student, enters his class, a number of portals suddenly erupt all around the two of them, from which terrible creatures attack them. Kuga quickly admits that he, too, is from the neighbor dimension.
