Mikasa Ackerman is the 'adopted' sister of Eren Yeager, and the main female protagonist of the series. She lived with the Yeager family for approximately a year before the fall of wall Maria. Though she desires only to live a peaceful life with Eren, Mikasa chooses to follow Eren into the military, where she would become the best soldier among the 104th Trainees Squad, and later join the Survey Corps.