A Choice with No Regrets: Part One (悔いなき選択 (前編) Kui Naki Sentaku (Zenpen)?, also known simply as No Regrets: Part One) is the fourth OVA, Episode 0.5A, of the Attack on Titan anime. It was produced by Wit Studio and Production I.G, and it was followed by A Choice with No Regrets: Part Two on April 2015.
Both episodes are anime adaptations of the spin-off manga Attack on Titan: No Regrets, illustrated by Hikaru Suruga and written by Gun Snark, and based in turn on the visual novel "A Choice with No Regrets", by Gun Snark.
In the underground, Levi and Furlan allow Isabel to join their criminal group and train her in the use of ODM gear. Soon after, they are offered an anonymous job with the reward of money and citizenship on the surface. During this job, they are caught by the Scout Regiment, led by Section Commander Erwin Smith. Recognizing their talents, he offers to overlook their crimes if they join the Scouts, and Levi reluctantly accepts the offer.
Before the fall of Wall Maria, below Wall Sina in the underground district, Levi and his comrades Furlan Church and Isabel Magnolia are operating a heist. By using their omni-directional mobility gear, they knock over supply crates owned by merchants, allowing one of their comrades grabs some of the contents and escape on foot. The merchants then call for the Military Police Regiment. Levi and his teammates notice that they are now being pursued.
Earlier on, Furlan is seen at what appears to be his and Levi's accommodations, distributing profit money to his comrades. While handing out everyone's cut, he slips a large sum of extra money in with his teammate Yan's pay. After everyone else leaves, Furlan proclaims that their jobs have been far easier since they acquired mobility gear and that they have been making more money. Levi notices Furlan is favoring Yan and asks him why. Furlan explains that Yan is having problems with his leg again and the price of medicine has gone up. The extra large sum of money is Yan's severance pay, because he will not be able to do this anymore. Furlan wonders aloud, how much more they're going to need before they can live on the surface.
Levi and Furlan hear a slam against their door and both jump to their feet. They draw their knives, get into a safe position, and swing the door open, only to see Isabel fall on the floor inside with her arms to her stomach. Furlan states that he was surprised by it only being a kid, and Isabel angrily denies that she is a child. She slowly gets up, revealing a small bird she is holding against her stomach.
They hear voices and Levi realizes she is being pursued. He and Furlan stand on either side of the doorway as her pursuers call out to them, asking if they saw a "dirty little kid" around this area. Furlan mockingly states that those are the only kind around. As the pursuers approach they notice Isabel sitting against the door and demand that they hand her over for trying to get past the #11 stairs without paying. Levi and Furlan can be considered guilty as well for harboring her.
As one of the men walk up to grab her, he placed his hand on Levi's shoulder. In response Levi immediately slices his hand with his knife and punches him several times for touching him with his filthy hand. He then shoves him down the stairs and he is caught by his comrades, who decide they are better off leaving. Levi turns to Isabel and asks her how long she is going to hold the bird to her chest, claiming it will die. Isabel thought it would be warm that way and lifts her arms to give it air. She explains that the bird got lost and she wanted to bring it to the surface because she knows it would rather fly in the sky than underground. Furlan is fine with that, but that the bird's wings are injured. He bandages them and the three exchange names and introductions. Isabel asks to become one of them and claims how envious she is of the way they fly around "like birds" using their mobility gear. After brief thought, Levi states that she must learn to clean before she can learn to use mobility gear.
Isabel gradually learns to use mobility gear. She is shown cleaning with Levi and Furlan, and also eating around a fire where she offer Levi some of her bread, but he declines and tussles her hair. She is later shown using her gear with her comrades while being cheered on by the other members of their gang. Levi and Furlan are with Isabel at a cavernous opening leading above ground, where she releases the bird with its wings healed.
As the three are walking towards their home, they are stopped by a distinguished old man asking them about a job. They are not interested, but man says he has already paid in advance and points them to their comrade Yan being helped into a carriage. The man states that Yan's legs are done for if he does not receive treatment at a surface clinic. and that he needs treatment on the surface. Levi agrees to hear him out and the trio walk with the man up the stairs to the surface. Another man in a high class carriage says they can trust him by the fact he is taking the risk to meet them in person. He asks if they received his advance payment. Levi claims that they have not given an advance, so much as their client has taken a hostage. The man states that the reward for success is much more substantial. They will receive the right to live on the surface.
As the trio prepares for another heist, Furlan tells the others they he has received confirmation that Yan is in a first rate clinic and he knows the identity of the man offering their job. This is the real deal. Furlan asks if they are going to do it. Levi remembers that their client claimed that regardless of their acceptance, their targets would make contact and they would be unable to stay unrelated to the matter. Levi tells his teammates to act normal and if their targets appears, they start the job.
During the heist, Levi, Furlan, and Isabel knock over supply crates with their mobility gear and are pursued by what is thought to be only the Military Police. The three continue to evade them and Levi sees that there is a second squad coming up from behind their initial group of pursuers. They are wearing green cloaks.
Their cloaked pursuers overtake the Military Police and Levi states identifies them as the Scout Regiment. The trio split up and begin their job. Levi maneuvers into a building and exits after running to a different spot within. He dodges one soldier, but Miche Zacharius crashes down on him before he can get far. The two slam into a pile of crates and Levi draws a knife, engaging Miche in combat and knocking one of his blades away. Levi moves in to attack, but is intercepted by Erwin Smith. The two face off and Erwin tells Levi to stop and look around. Levi sees that Isabel and Furlan have been captured and he surrenders. Erwin proclaims that Levi is quick to reading a situation.
Levi, Furlan, and Isabel are shackled at the wrists and sit on their knees in front of Erwin. He asks them where they obtained their mobility gear and how they learned to use it, but they remain silent. When Levi refuses to answer if he was trained in the military, Miche grabs Levi's head and smashes his face into a dirty puddle. Erwin asks again where they learned to use their mobility gear and Furlan insists that they were all self taught. They had to learn in order to rise above their current living conditions; something that Erwin, as a person who lives in sunlight, would not understand.
Miche lets Levi up as Erwin kneels down to his level. Erwin introduces himself and asks Levi's name. Levi states his name and Erwin offers to make him a deal, claiming that he will not charge them for their crimes if they agree to join the Scout Regiment. Levi then asks what will happen if he refuses and Erwin states that they will be handed over to the Military Police, who are unlikely to treat them well. After a brief thought, Levi begrudgingly agrees to join the Scout Regiment.
Currently Publicly Available Information
The Underground City
Created as a result of a previous plan to move underground in order to escape the Titans.
However, the plan was aborted, and it has since become a slum of sorts, where paupers, criminals, and more live.
As there are very few opportunities for its residents to be exposed to sunlight, many inhabitants develop issues with their legs.