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: The Harsh Mistress of the City

The future that was taken for granted was broken by the attack of the Titans. Wall Maria was pierced, and even in the Quinta District where Mathias and his allies live, Titans appear. Due to this, the line of supplies is cut off from the country, and the citizens begin to panic. Rita, a soldier who had joined the brigade of occupation troops, tries to protect the town that has fallen into chaos, but due to the forceful methods the brigade put into action using actual Titans, the entire city becomes afraid. In order to meet up with Rita, Mathias takes the helping hands of a band of thieves...

Attack on Titan: The Harsh Mistress of the City Franchise