Neighbor

A Neighbor (ネイバー, Neibā) extraterrestrial race. Neighbors are invaders from other dimension. They attacked Mikado City four years prior to the start of the series.

History
4 years and a half before, invaders started attacking Mikado City. These beings known as Trion Soldier are the toy soldiers used to perform the raids.

World
It is confirmed that lots of fellow countries of Neighbor living in another dimension are currently in a state of war. Even if this is a battle between fellow Neighbor, the trigger is being used. In order to activate the trigger it is necessary to secure trion, as such the Neighbor send in Trion Soldier to Mikado City. People possessing a high trion ability get abducted, and then recruited in order to fight the war in the other dimension.