Attack on Titan: No Regrets

The young Erwin Smith is a rising star in the Survey Corps, humanity's only hope of defeating the man-eating monsters known as Titans. Ruthless and dispassionate, Erwin's mind is devoted to strategies and intrigue. But beneath Erwin's feet is another world, the Underground, where humans are born and die surrounded by the garbage the Capital throws away. Here, the criminal Levi survives on his wits and agility. But when these two ambitious men cross paths, who will prove himself stronger?

(Source: Kodansha USA)

Note: Includes the prologue and 2 extra chapters.

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).

Many years before becoming the famed captain of the Survey Corps, a young Levi struggles to survive in the capital's garbage dump, the Underground. As the boss of his own criminal operation, Levi attempts to get by with meager earnings while aided by fellow criminals, Isabel Magnolia and Farlan Church. With little hope for the future, Levi accepts a deal from the anti-expedition faction leader Nicholas Lobov, who promises the trio citizenship aboveground if they are able to successfully assassinate Erwin Smith, a squad leader of the Survey Corps.

As Levi and Erwin cross paths, Erwin acknowledges Levi's agility and skill and gives him the option to either become part of the expedition team, or be turned over to the Military Police, to atone for his crimes. Now closer to the man they are tasked to kill, the group plans to complete their mission and save themselves from a grim demise in the dim recesses of their past home. However, they are about to learn that the surface world is not as liberating as they had thought and that sometimes, freedom can come at a heavy price.

Based on the popular spin-off manga of the same name, Shingeki no Kyojin: Kuinaki Sentaku illustrates the encounter between two of Shingeki no Kyojin's pivotal characters, as well as the events of the 23rd expedition beyond the walls.

(Source: MAL Rewrite)

Attack on Titan: No Regrets - Prologue

Prologue chapter that was included only in separate booklet sold together with limited special edition of volume 1.

Attack on Titan: No Regrets - Prologue Franchise