Opening the Gate

 is the third chapter in the fifth volume and the 21st chapter overall.

Summary
After the killing of the two titan test subjects, everyone is having their Three Dimensional Maneuver Gear inspected and the logs checked. The search turns up nothing.

Still recovering from the last attack, members of the 104th Trainees Squad discuss what department they'll join. Armin, Conny and Annie discuss the whether or not they will join the Scouting Legion. Conny is frightened at the possibility and asks Annie about her opinion on joining the Military Police. She tells him that it's his choice to make and not hers. Despite his fears, Armin admits he's joining the Scouting Legion. Annie then asks him what he would do if he was told he would have to die. Armin states that if the reasons are good, then he'll gladly die. Annie thinks he's weak physically, but also admits he's strong at heart. She states that she is joining the Military Police for a personal reason. Jean, while making it clear that he's nothing like Eren, says that he's also joining the Scouting Legion.

The trainees are called to an assembly where Commander Erwin is explaining the situation. He tells them that the Scouting Legion is short of personnel. He then brings out Eren and tells them the importance of the new weapon. With Eren on stage, he tells the trainees the importance it means to mankind and gives a few details of the upcoming mission. Upon telling the crowd the survival rate of the next mission and the Scouting Legion in general, he dismisses those that don't wish to join. With most of the people leaving, Jean imagines a possible fate of himself and his friends, while Conny tries to talk himself into becoming a police officer. Sasha tries to convince herself to leave and join another faction. However, her fear prevents her from leaving and she shares the same sentiments as both Jean and Conny in having to face titans again. When the crowd clears, there are twenty one people who are inducted into the Scouting Legion. Among them Mikasa, Conny, Jean, Armin, Reiner, Sasha and most of the top ten of the 104th Trainees Squad. Jean is disgusted when he finally realises that he's now a scout and not a Military Policeman. Conny doesn't seem to care anymore, while Sasha is fearful that she might have to face the titans again. Berthold takes one last look as he watches Annie leave.

One month later, the Scouting Legion is ready to begin their mission to travel to the Shiganshina District. Due to the closure of the gate in the Trost District, they have to leave from the gate in the Karanese District and travel around the wall. As they depart, they immediately see a titan. Commander Erwin tells them all to keep advancing; the defense squad will take care of it. They are now on their way to Shiganshina, which is infested with titans.