Hange was on an exploration mission with the Survey Corps outside the walls.

*She saw movement in a bush in the forest and rushed to cut down the titan. As she slashed the bush, she realized it was a person. Her sword slashed theyr shoulder and the person collapsed on a trunk, unconscious. *

*After the mission, she carries the unconscious woman and places her in a bed in a room in the quarters. *

"How did a civilian got outside the walls?" she wondered, curious how they managed to escape.