It was announced at Jump Festa ’20 by Toei Animation that Daisuke Ashihara’s World Trigger manga would be receiving a third television anime season! The anime hasn’t been scheduled for a time frame yet; however, a promotional video and some key art were released along with the announcement.
World Trigger ran its first two seasons in 2014 and 2015, spanning a total of 73 episodes. There is no word on how many episodes the third season will have. The manga had gone on hiatus several times due to Ashihara experiencing complications from a gall bladder operation. The manga is currently being published in Shueisha’s Jump SQ magazine.
MyAnimeList.net describes World Trigger as follows:
When a gate to another world suddenly opens on Earth, Mikado City is invaded by strange creatures known as “Neighbors,” malicious beings impervious to traditional weaponry. In response to their arrival, an organization called the Border Defense Agency has been established to combat the Neighbor menace through special weapons called “Triggers.” Even though several years have passed after the gate first opened, Neighbors are still a threat and members of Border remain on guard to ensure the safety of the planet.
Despite this delicate situation, members-in-training, such as Osamu Mikumo, are not permitted to use their Triggers outside of headquarters. But when the mysterious new student in his class is dragged into a forbidden area by bullies, they are attacked by Neighbors, and Osamu has no choice but to do what he believes is right. Much to his surprise, however, the transfer student Yuuma Kuga makes short work of the aliens, revealing that he is a humanoid Neighbor in disguise.
A review of the first two seasons can be found here: https://www.theouterhaven.net/2016/04/world-trigger-review/
You can check out the promotional video and key art below:
