Lone Shadow in the Town That Never Sleeps

Lone Shadow in the Town That Never Sleeps (不夜街の孤影) is the 3rd chapter of the 10th volume and the 35th chapter overall of the Attack on Titan: Before the Fall manga, written by Ryō Suzukaze and illustrated by Satoshi Shiki.

Overview
Thanks to a timely intervention by Klarissa, Sharle is able to get away from the thugs. The leader of them, Leo, offers to take Sharle to Angel's shop on the edge of the Underground City. After proving herself to him, Angel starts to recollect his friendship with Xenophon and his assistant Corina before a Titan invaded Shiganshina fifteen years prior.

Summary
As Sharle gets surrounded by several thugs, she tries asking if any of them saw Angel go through here. One of them laughs, stating it is a bold tactic but will not work. After hearing her ask about Angel, the man asks if she is an outsider and scoffs at the thought of her being a blacksmith apprentice. However, he tells her there is a dump on the outskirts run by someone with the name Angel. Just then, Klarissa arrives and claims Sharle is her client, threatening the thugs to not harm her.

Back at her brothel, Klarissa explains that the group of thugs likes to hustle people in this part of town, but the leader claims they are more legitimate than others and introduces himself as Leo. He does confirm that Angel went past him and is shocked to hear that Sharle is looking for his help against fighting Titans. After hearing about the device Angel and Xenophon were working on, Leo agrees to take Sharle to where Angel's shop is. Leo goes on to say that many of those living in the Underground City are wary of outsiders and everyone can essentially rely only on themselves to survive. Leo admits that some of Sharle's story made sense with him and wishes that someday, they can all get out of the Underground and be seen by those on the outside as more than just criminals.

They eventually reach the outskirts of town and come to Angel's shack. Leo knocks on the door, announcing he has brought a guest to see him; after getting no response, Leo lets himself in. They see Angel working and Leo once again repeats that Angel has a visitor. Still getting no response from Angel, Leo starts to berate him but Angel suddenly stops. Glaring at the two, Angel hands over his hammer to Sharle and orders her to strike. Inspecting her work, Angel derides it as amateurish but notes that the fundamentals are good. He expresses surprise that Xenophon was capable of taking on an apprentice and asks if he has been well. After reminiscing, Angel hears that Sharle is the same age his assistant Corina was when she died. Angel recalls that he was only eighteen himself while Xenophon was in his thirties, yet all three were friends and rivals until the day Titans broke through Shiganshina.