The Have-Not
Aftokrator retreats, but the wounds of the war are deep. Border struggles to revitalize Mikado City, Yuma searches for the missing Replica, and Osamu remains unconscious. In his dreams, he recalls why he joined Border, and why he seeks to protect Chika.
Aired 28/06/2015EP 36 - The Have-Not

World Trigger
One day, a gate to another world suddenly opens in Mikado City. Aliens invincible to Earth’s weapons, called “Neighbors”, start coming over. Earth’s only line of defense is a mysterious group called the “Border” who are armed with weapons called “Triggers”.
Four years later, the city has recovered from initial attacks and citizens of Mikado City have started to get used to the Neighbor’s attacks. Yuma Kuga, a transfer student, and his classmate Osamu Mikumo find themselves fighting a Neighbor that suddenly appears. Osamu, who is actually a Border agent, activates his Trigger but is unable to defeat it. This leaves Yuma to activate his own Trigger and defeat the alien. Yuma reveals that he is not part of Border and is actually a Neighbor who has transferred from the other side.
(Source: Crunchyroll)