Episode Title:A Visitor from a Strange World.Episode Description:In Mikado City's junior high school, a transferee named Yūma Kuga, who was late on his first day in the class, meets his classmate Osamu Mikumo. Kuga gets in trouble with the bullies in their class and is invited to an abandoned lot inside the Forbidden Zone, with Mikumo accompanying him. As the bullies are about to retaliate Kuga, a portal opens in the area, and a being from the other side, called "Neighbor", emerges. Mikumo then reveals himself to be an agent of Border, an organization that protects the city from Neighbors, and he saves the bullies from the attack using a Trigger weapon but gets pinned down by the Neighbor. Kuga then activates his Trigger and saves Mikumo, revealing that he is also a Neighbor.