The Trost District (トロスト区 Torosuto-ku?) is a town located on the south edge of Wall Rose. Because Trost is the town closest to the breach in Wall Maria, it is the town that most frequently comes under attack from Titans.
Five years after the fall of Wall Maria, the Colossus Titan appears again and breaks down the outer gate, causing the district to be invaded by Titans. Eren makes an attempt at killing the Colossus Titan, but it vanishes before he can reach its nape. After regrouping with the other trainees, he finds out they were too scared by the Titan to help him attack.
After the breach, the trainees engage the Titans in the district, resulting in huge casualties to the Garrison. Notable deaths include Thomas Wagner, Mina Carolina, Nac Tias, Mylius Zeramuski, Franz Kefka, Tom, Ian Dietrich, Marco Bott, and Mitabi Jarnach, among others. However, the entire civilian populace successfully evacuated in the hours immediately following the breach, thanks to the efforts of soldiers such as Mikasa Ackerman. Trost is also the district in which Eren Yeager and the other trainees discover his mysterious Titan ability, which prompts the Garrison under the command of Dot Pixis to devise a plan to seal the breach using a large boulder. The district is saved when Eren changes into his Titan form and successfully blocks the breached gate with the boulder. Soon after, the Survey Corps arrive and aid the Garrison in clearing out the remaining straggling Titans.
Shortly after the appearance of Titans in Wall Rose, Dot Pixis naps atop the Wall in Trost until his aide, Anka, awakens him with a slap. They discuss the low number of Titans and he surmises that this is because the Wall has not actually been breached. Erwin Smith arrives shortly thereafter and Pixis congratulates him for capturing the Female Titan. He hopes that the invasion of Wall Rose will convince the nobles in the interior to reconsider their motives.
On the ground, a Garrison soldier reports in, confirming that Wall Rose is still intact. The soldier then declares that three Survey Corps recruits from the 104th Training Corps are Titans. The Garrison's advance squad witnessed a fight break out on top of Wall Rose between the Corps and the Armored Titan and Colossus Titan, but the fight had finished before they were able to help. Erwin then departs Trost with a combined force consisting of members of the Survey Corps, Garrison, and Military Police.
After the costly rescue of Eren Yeager, Erwin Smith recuperates in Trost. Hange Zoë and Connie Springer brief him on their theory about the true identity of Titans, based on evidence regarding Ragako and its residents. Erwin smiles, knowing that this knowledge brings them closer to the truth. Hange then informs him that Eren and Historia Reiss are in hiding, lying low until the chaos dies down and that the Survey Corps has a plan.
Levi Ackerman and his squad leave their cabin hideout before associates of the Military Police Brigade's First Interior Squad can capture them. They head for their rendezvous point in Trost where they find the town in terrible shape. People blame the Survey Corps and the Titans for the loss of business and social stability. In the middle of a public confrontation, a carriage barges through and kidnaps two members of the squad.
Having anticipated this, the kidnapped victims are not Eren Yeager and Historia Reiss, but a disguised Jean Kirstein and Armin Arlert. Levi and his squad track the kidnappers to their hideout and successfully capture their ringleader, who turns out to be Dimo Reeves, the head of the Reeves Company. Reeves confesses that he does not want to help the Interior Squad so much as he is forced to. He considers Trost his town and gives people work. If he does not cooperate, the company will have be seized by the government and his employees thrown into the street. The lives of him and his subordinates would be forfeit.
Understanding the stakes and Reeves' resentment of the Interior Military Police, Levi proposes a deal. They will hand over Eren and Historia so the Reeves Company can survive, and in exchange, the Reeves Company will join the Survey Corps in opposing the Royal Government. In addition, the company will trust the Survey Corps and give them priority access to luxury goods. Reeves considers it a greedy bargain, but accepts.
After Eren remembers a portion of Ymir's conversation with Bertolt Hoover, Hange Zoë takes his notes and meets up with Erwin Smith in the Survey Corps office in Trost District. Hange informs him that Ymir's experience suggests that the power of the Titans can be transferred from one individual to another. If Eren's "scream" ability can be transferred as well, then the government will likely have someone eat Eren rather than leave the power with an uncooperative teenager.
Erwin hands Hange a report with the results from a team that had infiltrated Rod Reiss' estate. Before she can read it, a soldier interrupts to let them know that the Military Police's First Interior Squad was demanding to meet with Erwin about a murder. Understanding that he might not get another chance, Erwin names Hange his successor as Commander of the Survey Corps.
In the middle of town, one of the Interior MPs informs Erwin that Dimo Reeves and two of his employees have been murdered. The Survey Corps is blamed for their deaths, turning public opinion against them. All members are ordered to cease activity and appear before the Military Police. As Erwin is taken away, Hange escapes and meets up with Dimo Reeves' son, Flegel, who is watching the commotion, fully aware that it is all a lie.
Flegel, who had been hiding in the town, ended up cornered by members of the Interior Military Police inside some seemingly abandoned ruins. Flegel delays his execution by coaxing the MP into explaining why they killed Dimo Reeves. Hange and Moblit then jump from a building and incapacitate the MPs. Trost civilians come out of hiding, having heard the MP's confessions concerning Dimo, and all agree to bear testimony to the Survey Corps' innocence. The truth is also spread in the Berg Newspapers extra edition. With this, public opinion is turned back in the Survey Corps' favor.
Two months after Historia is crowned, Hange Zoë, with the help of Eren's hardening powers, builds a device that can kill Titans without exposing soldiers to them. It is built on the sealed gate and works similar to a guillotine, smashing the Titan's nape with great force.
The Survey Corps command hold a meeting, finalizing preparations for the operation to retake Wall Maria. They discuss Grisha Yeager, and what they expect to be inside of his basement. After the meeting's conclusion, Levi attempts to convince Erwin to stay behind, letting Hange take command over the forces. Erwin, however, refuses to stay behind and expresses his need to be present when they learn the truth of the world. At night, a feast is held for the Survey Corps in anticipation of retaking Wall Maria.
The next day, just before sunset, the Survey Corps ride the lift to the top of the wall. They are met and saluted by leaders of the military branches. The civilians of Trost, including Flegel Reeves, come out to give the Survey Corps a send-off, wishing them good luck in retaking Wall Maria. After enthusiastic cheering, Erwin Smith commences the final operation, setting out from Trost to Shiganshina District.
The military leaders wait at Trost over the course of the operation, until the remaining Survey Corps members return victorious. At a later date, Queen Historia travels to Trost, being delivered a letter written by Ymir, and overseeing a meeting to establish how the military should proceed following the discoveries of the basement. After long deliberation, it is decided to make the basement discoveries public knowledge.
- The name "Trost" means "solace" or "comfort" in German.