Battle of Trost District arc
Before having the chance to fully apply in the Scouting Legion so she can keep Eren safe, the Colossal Titan breaches Wall Rose the same way it did with Wall Maria. Much to her dismay, Mikasa is assigned to the rear guard to help fend off the Titans while the civilians escape into the safety of Wall Shina. Mikasa, before fulfilling her duty, makes Eren promise her not to do anything reckless. Later on, as an abnormal Titan approaches the escaping civilians, Mikasa kills it, saving everyone. She then witnesses why the civilians are taking too long to escape: a cargo blocking the way. Mikasa asks the businessman to move the cargo so that the people would escape, but when he refuses, Mikasa threatens him, which scares the businessman. Seeing a mother and daughter being grateful to her, Mikasa for a moment is brought back to the time she lost her own parents and realizes that Eren is the only family she has. Thus, with the evacuation of Trost District citizens complete, she heads to the front guard in order to aid her comrades. However, the sole trainee survivors are low on gas, making them unable to scale the wall while the supply team inside the headquarters has barricaded themselves in against the onslaught of multiple Titans. After hearing Eren's supposed death, Mikasa calmly regroups the survivors to break through the Titans assaulting the headquarters. However, due to her not rationally thinking after hearing Eren's supposed death, she does not notice that she's running out of gas. As two Titans close in on her, she contemplates giving up and begins to remember her time with Eren, when suddenly, she remembers Eren yelling at her to fight, which gives her motivation. When Mikasa prepares to kill a Titan reaching for her, another Titan arrives and kills the other Titan. This Titan, which ignores Mikasa, gives Armin enough time to rescue Mikasa and they both continue heading to the supply HQ. As they watch this rogue Titan continue killing other Titans, they hatch a plan to lure it to the HQ and relieve the siege there. With its help, the trainees manage to successfully refill their gas tanks and have clear access to the Wall.