Moonlit Oath

Gekka no Yakusoku (月下の約束) is the 3d chapter of the 1st volume and the 3rd chapter overall of the Attack on Titan: Before the Fall manga, written by Ryō Suzukaze and illustrated by Satoshi Shiki.

Summary
Driven by a sense of duty and want for a meaningful existence, Sharle Inocencio makes her way towards Kuklo's cell. As he sits in silence, chained to the floor. She opens the door, poised to stab him, in the hopes that she can save her town from the "Titan's child." As he looks at her she hesitates, unprepared for whom she saw. As she prepares to stab him, the knife slips out of her hand onto the floor. Before she can get to it, Kuklo picks it up and places it firmly in her hand; placing it directly in the center of his own body. Shocked, she questions why he would want to die. Then states she came down there to kill him, as she speaks he repeats "resist" several times. In disbelief that a Titan can speak. After he begins repeating "Xavi", she begins to wonder if he is really a Titan at all.

he is suddenly brought to his knees from terrible hunger pains. Not knowing much else he begins repeating "resist" again. Sharle hurries out of the room, leaving her knife behind. Before long she comes back with a basket full of food. As his mouth waters she places it down in front of him. As he eats, she wonders if he is a Titan. Based on the things she is seen and read, she believes he is just a regular human. When he finishes she asks him his name, to which he replies "Kuklo"; she then gives hers.

As the night goes on she wraps him in her shawl to keep him warm as they talk about Titans. She shows him a hand drawn map of all three territories, saying each wall's name as she points to it. She mentions that humans can only live within the Walls. As Kuklo points to a "person" outside the wall, he tells her "There's a person here..."; to which she tells him it is a Titan. He decides that in order to confirm he is a human he must meet a Titan. He asks Sharle to tell him about the outside world, realizing that is the only way to achieve his goal.

Sharle spends half a year teaching Kuklo, and preparing him for the outside world. But regardless of how much knowledge he gained, it was useless so long as he remained chained up. So he developed a plan that would not arouse suspicion. It involved using sweat, blood, urine, and other things like it to slowly corrode the chains until they were weak enough for him to break free; a process that took two years to complete. It was clear to him that Dario Inocencio and Xavi would never release him, so this was the only way.

Two years later while having dinner, Xavi and Dario begin discussing what to do with Kuklo. With Xavi on his way to the Trainees Corps, there was no need for Dario to keep him around. While Sharle is lost in her thoughts, Dario mentions that soon she will be busy too. He continues on to say that the marriage proposals are being finalized.

Back in Kuklo's cell he contemplates when would be a good time to leave. Shortly after, Sharle enters his cell. With her head kept low she begins crying, she tells him Dario's plans for both him and her. He encourages her to leave with him. She is hesitant, believing she is too weak to make such a decision. But he reaches out his hand and tells her, "Let's go together. Leave it to me." With hand in hand their plan is decided.