Attack on Titan: No Regrets (2013)

2 Ova's, The story is a prequel to Attack on Titan, and follows Levi during his days as a criminal in the underground city, before Erwin Smith recruits him into the Survey Corps. 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?
The long-awaited origin story of Levi and Erwin, two of Attack on Titan's most beloved characters!