Attack on Titan: Lost Girls (Novel)

Attack on Titan: Lost Girls (進撃の巨人　ＬＯＳＴ　ＧＩＲＬＳ) is a novel and compilation of three stories written by Hiroshi Seko, a scriptwriter for the Attack on Titan anime. The first two stories, "Wall Sina, Goodbye" and "Lost in the Cruel World" are based on the visual novels of the same names, released on the Blu-ray copies of the anime. A third story, "Lost Girls", was a new release. The three stories were also adapted into a manga of the same name.

Lost Girls
Written by Hiroshi Seko. In their days in the 104th Training Corps, Mikasa wonders why Annie acts the way she does and what burden she carries.