Mikasa is Eren’s adoptive sister and mutual childhood friend of Armin. Mikasa shares an unbreakable bond with Eren following events in their past, and rushes to protect him whenever he is in danger. Mikasa possesses impressive fighting skill and strength even as a child.
As a teen, Mikasa is considered a genius among all the army trainees and is incredibly skilled at combat and agility. She constantly worries for Eren’s well-being and lives to protect him.
When Mikasa was younger, her parents were murdered and she was taken hostage to be sold into slavery. Eren managed to find her and killed two of the three kidnappers by catching them off guard, despite only being a child. The third kidnapper discovered the scene and began strangling Eren while holding him in the air. Mikasa, trembling, grabbed Eren’s knife from the floor. In that split second, Mikasa came to terms with the cruelty of the world, gaining perfect control of her own body and using that strength to kill the kidnapper in a single strike through the heart—killing him to save Eren.
In the aftermath of this trauma, Mikasa asked Dr. Jeager where she could possibly go from here. She was cold and had no place left to call home. Eren gave Mikasa his red scarf and Dr. Jeager welcomed her into their family. Because of Eren’s heroics and this gesture, she feels she owes her life to the Jeagers. She continues to wear Eren’s scarf from that day into adulthood, and they are inseparable.