Best Anime Ever - Attack on titans

The story of Attack on Titan revolves around the adventures of Eren Yeager, his foster sister, Mikasa Ackerman, and their childhood friend Armin Arlert. After the wall which protects their hometown of Shinganshina is breached by the Colossal Titan leading the other Titans to enter, Eren watches in horror as one of them eats his mother. Vowing to kill all the Titans, Eren enlists in the military, along with his friends.

Five years later, the three cadet graduates are positioned in Trost District, one of the border towns jutting out of Wall Rose when the Titans attack again. In the ensuing battle, Eren saves Armin from being eaten by a Titan, at the cost of him being eaten himself. A Titan later appears and begins fighting the other Titans while ignoring humans; the Titan is revealed to be Eren, who has developed the ability to transform into one. Though he is seen as a threat by some, he helps the military take back Trost District. After being placed on trial for being a danger to the humans, he is taken in by the Survey Corps' Special Operations Squad, led by Captain Levi.

In an expedition to Shinganshina, the Scouts are attacked by a Female Titan who attempts to capture Eren. Although the Scouts are able to briefly capture the Female Titan, she breaks free and devastates Levi's squad, forcing the expedition to retreat. Armin determines that the Female Titan is Annie, one of the cadets who taught Eren to fight, and devises a plan to capture her at Stohess. During this operation, collateral damage reveals that Titans reside in and make up the walls surrounding the human settlements.