|Eren... Listen... I need to tell you something. You've always... been at my side. Thank you. You showed me... how to live with purpose. Thank you. And you... You wrapped this scarf around me. Thank you.|
|— Mikasa shows her gratitude for everything Eren has done|
After Hannes is eaten by the Titan which killed Eren's mother, Eren suddenly unleashes an incredible power upon the Titan, causing the other Titans to swarm it and tear it to pieces before chasing Reiner and Bertholdt away. For her own reasons, Ymir leaves the Scouts and retreats with the Warriors.
The Scouts later conclude that the Titans which invaded Wall Rose were in fact, the human citizens of Ragako. As Eren devotes himself to discovering how to use his newfound power, a recovering Erwin concludes that the truths of the world will soon be known.
Memories of his mother's life and death flash through Eren's mind then the smiling Titan that killed her five years ago appears on the battlefield. Elsewhere, Reiner continues to throw Titans at the retreating Scouts. Ymir brawls with the Titans, outraged at Commander Erwin's hand in her plan's failure, and the commander is dismounted when she attacks a Titan pursuing him. Erwin's Scouts attempt to defend him, though Erwin places Eren's life above his own for the sake of the mission.
When the smiling Titan reaches for Eren and Mikasa, Hannes comes to their side, eager to avenge Carla for his inability to confront the Titan five years ago. Jean and Armin attempt to assist Hannes, but Reiner's Titan-throws prevent them from approaching. Meanwhile, the turn of events has Ymir questioning whether she is better off staying with the Warriors or the Scouts. While she believes the future of the Walls is bleak, now is her only chance to hand Historia over to the Warriors.
Historia approaches Ymir, saying that she believes that her actions were to protect her and not Ymir as she had been told. Historia reminds Ymir of her own words and urges her to live for herself, admitting that Ymir's presence inspires courage in her.
Together with Conny and Sasha, they team up against the Titans while Hannes continues to fight the smiling Titan. Mikasa, too injured to continue fighting, unties Eren's restraints so that Eren can transform and fight the Titan. However, when he bites his still-healing hand, he is unable to transform.
Scouts continue to defend Erwin as the Armored Titan throws more Titans, dismounting Jean. Armin comes to his side, carrying him away from the combat.
Eren desperately attempts to trigger his transformation while the Titans devour the Scouts, and Hannes nearly gains the upper hand over the smiling Titan. Suddenly, the Titan catches Hannes in its grip, and Eren and Mikasa are unable to stop it as it brings Hannes to its mouth, biting him in half. Eren collapses in anguish, laughing and screaming hysterically at his inability to prevent the tragedies around him.
Mikasa consoles him, assuring Eren that he has done much for her. She thanks him for being by her side, showing her how to live, and for giving her his scarf. Finding his resolve, Eren promises that he will wrap her scarf around her as many times as she needs.
As Eren's hand finally heals, he lets out a scream as he swings his fist into the hand of the smiling Titan. Suddenly, Reiner, Bertholdt, and Ymir feel a surge of power emanating. As Eren screams, a newfound power comes forth and a Titan tackles the smiling Titan. The other Titans nearby redirect their attention from the Scouts to the smiling Titan, charging and swarming it before tearing its body to pieces. As Eren carries Mikasa away from the scene, the other Scouts continue their retreat. Understanding the situation, Ymir realizes that there may yet be a future for the Walls.
Reiner runs for Eren, recognizing that Eren indeed possesses the Coordinate the Warriors have been searching for, who Reiner believes he is the worst possible person to possess its power. Eren cries out to Reiner and Bertholdt, ordering them under threat of death to stay away from him. The Coordinate comes forth again in response to Eren's scream, and the Titans devouring the smiling Titan turn their attention to Reiner and Bertholdt, charging towards them. Armin brings a horse for Eren and Mikasa, and Commander Erwin orders for a full retreat.
As the Titans rush Reiner, Bertholdt cries out in fear as he is unable to defend himself. Ymir hears his cries and stops to look back. Turning to Historia, she gently caresses her hair and apologizes before running for Reiner and Bertholdt. As Historia looks on in confusion, Conny turns her away to join in the retreat. Meanwhile, Ymir aids Reiner in fending off the Titans, and the two Warriors are shocked by her sudden change of mind.
As the Scouts ride for Wall Rose through the dusk, Armin is unable to understand Ymir's choice, and Eren thinks back to his childhood with Hannes in peaceful times.
At night, the Warriors and Ymir arrive in the ruins of Shiganshina, exhausted from the past few days. Reiner asks her why she chose to come with them, and Ymir says that she wanted to return the favor for their hand in giving her a second chance at life when she stole the Titan power from their friend. Furthermore, she believes that she is the only one who understands the situation the two are facing. Bertholdt thanks her and apologizes, and Ymir muses that it was not a bad life being a goddess.
Refugees from Wall Rose had been sent to the underground city in Wall Sina at the outbreak of the Wall Rose invasion. However, food supplies only guarantee proper treatment for the refugees for one week before the risk of civil conflict began. To prevent this, the military declares Wall Rose Titan-free one week after the start of the outbreak.
At this time, Erwin recovers from his injuries in Trost District, accompanied by Commander Pyxis and Captain Levi. They are visited by Section Commander Hange, who brings Conny to inform the others of the Scout Regiment's recent findings in Ragako. Elsewhere, Eren comes to terms with the fact that over half of the Scout Regiment's veteran soldiers died in the attempt to rescue him from the Warriors.
However, during their final retreat, the Scouts went unhindered by the Titans that continued to chase after Reiner and Bertholdt. Armin informs Eren that he and Jean believe that Eren could be the only one responsible for the sudden power which made the Titans obey his will. Jean pities Eren's responsibility, and he reminds him of the effort he must show to prove that the lives lost for his sake were not in vain. Eren understands, vowing to master his power over the Titans and to exact his revenge on the Warriors.
In Erwin's room, the officers learn that all evidence suggests that the citizens of Ragako were the Titans which invaded Wall Rose, meaning that the Titans are in fact, humans. Levi worries at the notion that he has spent his years in the Scouts killing humans all along. Hange says that they do not have any real proof of the claim. Strangely, Erwin cannot help but smile at the news, which disturbs Levi further.
When asked about his behavior, Erwin stoically states that humanity has come one step closer to the truth. Levi worries that no one will be left to see the full truth in the end, though Erwin is confident in the step they have taken towards breaking down the walls barring humanity from the truths of the world.
Currently Publicly Available Information
Through extensive research and accounts of various incidents, it has become clear that the scourge of Titans which have long plagued humanity are of human origin. The Colossal Titan which destroyed the wall at Shiganshina District is a human possessing the ability to transform into a Titan, demonstrated by its intent to breach the wall with the purpose to exterminate humans. Titans are not sent by the heavens to punish us for our sins, but invaders that must be driven back. Thus, we swear, by the blood of our brothers and comrades spilled waging war against this foe, we shall not relent our lands nor yield the fight.