Attack on Titan (進撃の巨人 Shingeki no Kyojin, lit. "Advancing Giants") is a Japanese manga series written and illustrated by Hajime Isayama. The story centers around the lives of Eren Yeager, his adoptive sister Mikasa Ackerman, and their friend Armin Arlert, who live in a world where the remnants of the human population live inside cities surrounded by enormous walls due to the sudden appearance of the Titans, gigantic humanoid creatures who devour humans seemingly without reason. Their lives are changed forever after the appearance of a colossal Titan brings about the destruction of their home town and the death of Eren's mother, spurring them to enter the army to battle the Titans themselves.
An anime television series debuted on April 6, 2013, on MBS.[Note 1] A live action film adaptation is also in production. Four video game adaptations developed by Nitroplus staffers in collaboration with Production I.G were announced to be released as bonus content for the third and sixth volumes of the Blu-ray Disc release of the anime.
The manga series has become a commercial success, selling over 20 million volumes as of mid 2013. The release of the anime also saw a boost in the series' popularity with several writers critically acclaiming for its atmosphere and story. Although it also gained fame in neighboring Asian countries, the series's themes have been a subject of controversy