Mikasa Ackerman

Mikasa Ackerman (ミカサ・アッカーマン) is the female protagonist of the series and the adopted sister of Eren. After graduating as the top of her batch, she later joins Scouting Legion with Eren and Armin.

Personality
Mikasa is considerably more withdrawn after the murder of her parents; however, she still loves and cares deeply for her friends, such as Eren and Armin, seeing them as the last remnants of a family she cannot afford to lose. Mikasa has a strong sense of right and wrong, but will always follow Eren and his decisions. When he once said that her hair was too long, she immediately had it cut, even though Jean had just commented that it looked beautiful. Yet, for all her blind loyalty, Mikasa is also very level-headed. Even though it was believed that Eren was dead, she concentrated on keeping everyone else alive and not giving in to grief as many of her comrades are doing. If Eren is in danger, Mikasa will stop at nothing to keep him safe, to the point of being willing to kill soldiers who try to execute Eren and relentlessly attacking the Female Titan when she captured Eren.

History
Mikasa and her mother are the last of their clan and the oriental race. Before her parents' death, she lived peacefully with them in the farmlands of Wall Maria. Mikasa underwent a painful scarring ritual from her mother, whom cut into her skin the mark of their oriental clan. Being the last of their race made them high value targets to human traffickers, who killed Mikasa's parents and kidnapped her when she was only 9 years old. She is rescued by Eren who tricks and kills two of the slavers. He was then overwhelmed by the third trafficker and on the verge of being strangled. Desperately, Eren urges Mikasa to fight to win. Although she was initially frightened, she came to realize that "this world is a callous and merciless place" and dispatched the kidnapper who was trying to kill Eren. This event awakened the fighting instincts and perfect self-control that would later turn her into a formidable soldier. She lived with Eren's family in Wall Maria's Shiganshina District until the beginning of the story.

Transformation Arc
Mikasa, upon graduation, is ranked first. 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 with Annie 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 a 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 (unintentional) help, the trainees manage to successfully refill their gas tanks and have clear access to the Wall. However, as they watch the rogue Titan dispose of the last Titans surrounding them, Eren appears out of its spine. Overcome with relief that Eren is alive, Mikasa quickly rescues and embraces him and together, everyone leaves for the Wall.

However, their commander fears Eren is a Titan and attempts to have Mikasa and Armin executed along with him. After a tense standoff, they are saved when Commander Dot Pixis, head administrator of the southern region, intervenes. They are sent on a mission to stopper the breach in the Wall with a rock that only Eren in Titan form can lift.

As the mission commences and Eren goes into Titan form, he attacks Mikasa and eventually knocks himself out. The elite team designated to defend Eren as he carries the rock quarrel among themselves about what to do next. Mikasa was on the verge of attacking them until the team leader orders everyone to continue protecting Eren until he recovers.

Eren eventually snaps out of it and successfully places the rock down. However, he is brought before a military tribunal to decide his future. Despite Mikasa's best efforts to defend him, she is forced to testify against Eren as his reckless actions have frightened many people in the courtroom.

The Female Titan Arc
Sometime later, Mikasa and everyone else were having their Three Dimensional Maneuver Gear(3DMG) inspected and in order to find out which 3DMG was used to kill the two captured titans. Later on, Commander Irvin Smith comes to recruit new members for the Scouting Legion which is scheduling an expedition within a few months. Many left except for Mikasa, Reiner, Armin, Sasha, Christa, Conny, Jean, Berthold and a few others.

Shortly after leaving for Wall Maria, the Female Titan appeared and given her knowledge of military formation, she was able to defeat the Scouting Legion. After kidnapping Eren, Mikasa teamed up with Rivaille and attacked the Female Titan relentlessly until they got Eren back. Following the Scouting Legions' failure, Armin had convinced Annie to help them out until they can gather evidence to prove to the King that the walls need to be protected better. During that time, Mikasa took notice of the lack of diligence and honor in the Military Police. She prepared for battle when she got fed up with Annie's games and excuses. She took off her disguise and drew out her 3DMG to fight her. Mikasa calls her out as the Female Titan who attacked them earlier.

Mikasa learned that Eren in his titan form isn't powerful enough to defeat Annie by himself. Being the strongest and most powerful soldier herself, she decides to take the fight to her. Despite being ordered to pull away from Lt. Hanji, Mikasa manages to make it to Annie as she attempted to climb over Wall Shina to escape to the flat lands. She cuts off all her fingers and pushes her off to fall to the ground. Annie is therefore captured, but encases herself in a crystal to avoid interrogation. However, it was far from over as Mikasa has just taken noticed of a titan hiding behind the wall, similar to the Colossal Titan.

As both the Scouting Legion and Military Police takes an encased Annie underground to detain her, Mikasa realizes the Titan hiding in Wall Shina is breathing, but is too weak to move due to a lack of sunlight. Mikasa remains at Eren's bedside as Armin and Jean head down to a meeting involving Commander Smith and the Military Police.

Breach Arc
Mikasa, Eren and the other members of the Scouting Legion comes to rescue Reiner and the others from the other titans. She was among the others who learned Christa's real name being Historia. Mikasa is outraged when she overhears Reiner confessing that he and Berthold were responsible for the attack on Wall Maria, 5 years ago and wanted Eren to join them. She took them by surprise by attacking them and told him to run. As Eren battles with Reiner, Mikasa faces her own troubles and regretted not cutting off both his and Berthold's heads when she had the chance. During the fight with Reiner, she saw Eren in trouble and tried to fight him off. However due to the thickness of the armor, Mikasa had a hard time slicing the nape of Reiner's neck.

During a flashback, Mikasa asked Annie to teach her a move that she was teaching Eren, which eventually called for a bet with the 104th Training Class to see whom was the stronger fighter. Eventually, Armin saw a weak link in Reiner's line of defense in which his armor is breaking and gives Mikasa extra blades to replace her own. Taking advantage of the information, she cut his at the back of the knee caps and it turned out to be his weak point.

In Ch.45, Mikasa along with Hanji and others from the Scouting Legion are injured from the heat blast from Berthold's titan from. While Armin helps them recover, he gives Mikasa the news that she was dreading to hear: Eren along with Ymir was kidnapped by both Reiner and Berthold. Taking the scarf that he gave her, Mikasa covered her face with it and asks why Eren always runs off on them like that. When she previously fought Annie in her titan form, Mikasa and Rivaille were able to recover him back. This time, she feels like she has failed in keeping her adoptive mother's promise in always protecting him and wept. As Armin tried to console her, Hannes arrives to give out rations to the Legion. It was he who reminds her that despite him running off the way he does and often losing fights, he never gave up on them. Even thought the odds were stacked against him and is unwilling to admit it, Hannes always knew that Eren relied on both Mikasa and Armin when he needed them. His words and his assistance reinvigorated them and are more determined to rescue Eren. Mikasa lowered her scarf and begins eating. Feeling the same feeling that Historia has in wanting to rescue Ymir, she took her stance with the Scouting Legion.

Abilities
Even in her younger years, Mikasa has been a talented fighter, often throwing boys bigger than her with ease, gaining her reputation. An example of this is when Armin was being bullied and Eren came to his rescue. The boys were preparing to take Eren on when they saw Mikasa behind him and promptly ran away. While she was still training, Keith even denoted that Mikasa's performance is exemplary in every subject, and that she is truly a genius. Combined with her prodigious skill in 3D Maneuver Gear, she can easily take down Titans with speed and efficiency. This has lead to her being mentioned as a military genius many times and "worth a hundred ordinary soldiers". This has been proven true when she took on Annie in her Titan form.

Trivia

 * Mikasa ranked third in the characters popularity poll.
 * The scarf she always wears was given to her by Eren after saving her from the slavers.