Attack on Titan

A century ago, the grotesque giants known as Titans appeared and consumed all but a few thousand humans. The survivors took refuge behind giant walls. Today, the threat of the Titans is a distant memory, and a boy named Eren yearns to explore the world beyond Wall Maria. But what began as a childish dream will become an all-too-real nightmare when the Titans return and humanity is once again on the brink of extinction … Attack on Titan is the award-winning and New York Times-bestselling series that is the manga hit of the decade! Spawning the monster hit anime TV series of the same name, Attack on Titan has become a pop culture sensation. 

(Source: Kodansha Comics)

Volume 3 contains the special story "Rivai Heishichou" (リヴァイ兵士長, Captain Levi).
Volume 5 contains the side story "Ilse no Techou" (イルゼの手帳, Ilse's Notebook).

Attack on Titan Volume 0

Shingeki no Kyojin Volume 0 contains prototype of original manga never published before, drawn by Isayama Hajime when he was 19 years old, for "Magazine Grand Prix" in 2006.

Attack on Titan Volume 0 Franchise