World Trigger

World Trigger (ワールドトリガー, Wārudo torigā) is an ongoing Japanese manga written and illustrated by Daisuke Ashihara that has appeared in Shueisha's  magazine since February 2013. After a long hiatus, it was announced the manga will instead continue in the monthly magazine .

Background
Ashihara was a large fan of Doraemon, and was inspired with the idea of using future technologies in the present.Before creating the story, Ashihara created the characters and the world. He placed that characters in different roles to see what would work.In the original concept, Yūma was a Border agent, and Osamu was a human who wasn't in Border. Ashihara wanted to create a concept of opposites, so he made Yūma a powerful Neighbor, and Osamu a weak Border agent.

Plot

 * See also: Manga

One day, in Mikado City, a gateway to a parallel universe had opened. From it, an outbreak of aliens known as Neighbors wreaked havoc across the city with their own sophisticated technology. Suddenly, a mysterious group of people brought themselves together to repel their attacks. Soon after, Border was formed, an organization researching Neighbor technology and maintaining a defense system against the Neighbors. Its members are armed with weapons known as Triggers. Four years later, the city has recovered from initial Neighbor attacks to the point where its civilians have become used to them.

Yūma Kuga is a transfer student from a foreign country admitted to a local school. There, he meets fellow classmate Osamu Mikumo and a group of bullies harassing the two. After fighting off the bullies, a Neighbor appears. One of the bullies is about to get eaten, but Osamu, actually a member of Border, activates his Trigger, but fails to defeat the Neighbor, leaving Yūma to activate his own Trigger and defeat it successfully. Yūma reveals he isn't actually part of Border, and that his Trigger is a memento of his dead father who wanted him move to Japan to join the Border. He also reveals his father wasn't part of Border either, and that he actually transferred from the alternate dimension where the Neighbors come from. He came to find his father's acquaintance. Following this revelation, a Rad Infestation takes place where Rads hid in various locations within the city (outside of the Danger Zone) and opened gates for Trion Warriors to pour in. One of these places was the school, where Osamu failed to stop them, but Yūma used his Trigger and Osamu's to defeat them. Because using training Triggers outside of Border was illegal, Osamu is taken for punishment. Along the way, an Ilgar attacks the city, and Yūma is forced to use his Trigger to save civilians, alerting Border of his existence. He helps solve the Rad mystery. With Osamu's suspicious defeat of the Mole Mod that attacked the school, Miwa Unit begins monitoring him. At the same time, Osamu introduces Chika Amatori to Yūma, a girl who attracts Trion Warriors. Yūma reveals this is because of her abnormally large Trion amount. Miwa Unit, having surveyed Osamu, discover Yūma. Yūma easily defeats them in a battle with his Black Trigger, so Kido orders the capture of the Trigger.

Yūichi Jin, an S-Class agent of Border affiliated with Tamakoma Branch, invites Yūma to join Border. Yūma discovers that his father's acquaintance, Sōichi Mogami had passed away by becoming Jin's Black Trigger Fūjin, leaving him with hardly any motivation to remain on Earth. Replica reveals Yūma's other goal to Osamu, so Osamu has Yūma join him in a team to recover Rinji Amatori and Aoba Harukawa. Yūma agrees. While being introduced to Tamakoma Branch, Jin engages with the assault force assembled by Kido which consists of Tachikawa Unit, Fuyushima Unit, Kazama Unit, and Miwa Unit. With the help of Arashiyama Unit, he defeats them. To ensure Yūma's safe enlistment into Border, he gives up Fūjin.

Yūma and Chika enlist into Border and make a flashy debut. Even Osamu becomes famous for tying with Sōya Kazama, the No. 2 Attacker (although it took him over 20 battles). However, a new threat emerges: a Second Large-Scale Invasion. The Neighbor nation Aftokrator sent 6 agents to capture C-Class agents and find a "God". During this invasion, Osamu is slated to die if the invasion becomes its worst. A new Trion Warrior, a Rabbit, is used; capable of capturing agents and more powerful than the average B-Class fighter. With the entrance of humanoid Neighbors and Black Triggers, Border is met with superior technology, but using teamwork, they defeat their adversaries. Osamu is left severely wounded, but survives. His troubles are not over, though, as several C-Class trainees were kidnapped. It is speculated that him being defeated without Bail Out in front of the enemy Trion Warrior led to them learning of the C-Class lack of Bail Out. However, he manages to deflect this attention to the prospect of entering the Neighborhood and recovering the kidnapped personally. Following this, Border experiences a much higher application rate. At this time, the B-Class Rank Battles begin. Yūma and Chika have rose to B-Class, and have formed Mikumo Unit with Osamu. They participate in the Rank Battles and face various opponents. They win their first 3 battles with relative ease. However, their fourth match is a huge loss as they challenge the top B-Class units. The captain of the B-Class #1 Unit, Masataka Ninomiya, reveals that he has information regarding Rinji's disappearance. While this is gone, Aftokrator orders its vassal nations to cripple Border's offensive power. Galopoula sends its Expedition Force while Rodochroun send Trion Warriors. The objective is to destroy the Expedition Ship.

Main Characters

 * See also: Characters

Settings

 * Mikado City