|What was it that we found in that basement? Was it hope...? Or was it despair?|
|— Eren muses over the Survey Corps' discoveries|
To the Other Side of the Wall (壁の向こう側へ Kabe no Mukougawa e?) is the 4th and final chapter of the 22nd volume and the 90th chapter overall of the Attack on Titan manga, written and illustrated by Hajime Isayama.
At the military meeting, officers of the Military Police Brigade mention the inevitable social chaos that will erupt if the truths of the basement become known, though Pixis believes spreading the truth is a necessity. Historia sides with Pixis, and the meeting concludes. Later, Hange and Levi speak with Roy and Peaure of the Berg Newspapers about the mixed public response to the new information. While Roy is proud of the Survey Corps' accomplishments, he is afraid of the implications the basement's information brings.
Later, Hitch meets with the 104th recruits in the Survey Corps and learns of Marlowe's death from Floch. He argues with the others about the decision to save Armin over Erwin, and the situation grows tense. Armin sides with Floch, but Eren insists that no one can know what would have been better and reminds Armin of the freedom they seek beyond Wall Maria. Shortly afterward, Historia hosts a ceremony for the survivors of the battle of Shiganshina District, and Eren sees a memory of his father in the Reiss Chapel when he touches Historia's hand.
That winter, the Titan guillotine was used to eliminate all the Titans in Wall Maria, confirmed in the last weeks of the season. By springtime, transport beyond Trost District was made possible through elevators along the Wall. Finally, one year after the battle of Trost District, Shiganshina was repopulated and the Survey Corps set out beyond Wall Maria for the first time in six years. Following the trail of a Titan dragging itself on the ground, they reach the borderline of Paradis and come to the ocean. As the others play in the water, Eren contemplates the freedom they will achieve when they kill their enemies across the sea.
Upon hearing the Survey Corps' testimony, Military officials begin to worry that releasing such information about the outside world to the public will lead to chaos within the Walls. Pixis disagrees, pointing out that keeping information from the public will make the current government no better than the one they overthrew. Historia, swayed by Pixis' words, announces that the information recovered by the Survey Corps will be made public.
Sometime later, Hange and Levi pay a visit to Berg Newspapers. Roy and Peaure inform them that the secrets from Grisha's basement has been publicized. When asked how the news has been taken, Roy admits that not everyone is willing to believe what they have been told, and that chaos has descended as a result. Roy questions what they should do next, given the knowledge that the entire outside world wishes for the inhabitants of the Walls to be annihilated.
As the remaining members of the Survey Corps prepare for a ceremony in their honor, they are approached by Hitch, who has come to watch the ceremony. Jean assures her that Marlowe acted bravely on their mission, and asks Floch to recount the events to her. Floch praises Marlowe for staying calm and encouraging his fellow recruits, even after they had given up hope. However, he then admits that Marlowe likely regretted his actions his final moments. As Hitch leaves, an appalled Jean demands to know why Floch said such a thing to Hitch, and Floch tells him that someone should be honest about what happened.
Armin admits that he knows Floch wanted Erwin to live, and Floch claims that everyone who has read the Corps' report believes Erwin should have lived. Eren tries to defend Armin, but Floch accuses him, along with Levi and Mikasa, of allowing his personal feelings to keep him from making a rational choice. Floch accuses Eren of behaving childishly, and praises Mikasa for having the maturity to give up on saving Armin. Before things can escalate further, Jean intervenes. Floch, growing agitated, asks that they inform any future recruits of what they are truly signing up for, so that no more cowards like him join. Armin agrees that Erwin should have lived, but Eren insists that there is no way of them knowing for sure what the future has in store.
During the awards ceremony, Eren reflects on what he has learned, noting that, while he would gladly lay down his own life, he would not want to sacrifice Historia. As he kisses Historia's hand, Eren is granted a vision of his father's memory from the night Wall Maria fell. Upon arriving at the Reiss Chapel, Grisha revealed his origins from beyond the Walls to the Reiss family, and begged Frieda to destroy the Titans before they devoured everyone in the Walls.
One year after the Battle of Trost District, after 9 months of work clearing Titans out of Wall Maria, citizens are finally permitted to return to Shiganshina District. Soon after, the Survey Corps mounts its first expedition beyond Wall Maria in six years. Levi observes that, as Hange hypothesized, most of the Titans had been inside of Wall Maria, leaving the area outside the Walls mostly empty. The Corps encounters a single Titan, which is unable to stand upright due to its disproportionate body. Eren notes that the encounter with the Titan means they must be close to the spot where Marley turns Eldians into Titans.
The Corps arrives at the site of the Eldians' transformations and the ocean in short order. As his comrades inspect the water, Armin is left mesmerized. Armin is thrilled to have been proven right about the ocean, but Eren is melancholic. He reminds them that the freedom they thought was beyond the Walls will not exist until they kill all of their enemies in Marley.