The Fall of Shiganshina arc

 is the first story arc in the Attack on Titan anime.

Introduction
The story begins inside the walls of humanity and the main protagonists are shown, Eren Yeager, Mikasa Ackerman and Armin Arlert. However, a mysterious threat known as the Titans lurks outside these walls and the children soon learn of their terror as the Colossus Titan breaks through the gate to their home, Shiganshina District.