Those Three

 is the 3rd chapter of the 2nd volume and the 7th chapter overall of Attack on Titan: No Regrets, written by Gun Snark and illustrated by Hikaru Suruga.

Summary
Having lost sight of the rest of the Survey Corps in the rain, Furlan Church decides that the only thing to be done is to keep moving forward and hope that the rain stops quickly, stating that if Flagon Turret's noise rounds are still in working order, they should be able to find him. Isabel Magnolia laments the fact that their vision is obscured by the fog, stating that it feels as though the Titans are constantly breathing down her neck. Furlan jokes that if Erwin Smith is devoured by Titans, it will be impossible to ecover his documents, and suggests heading toward the center of the scouting formation to take the documents from him. Hearing a noise through the rain, Levi Ackerman silently debates whether all three of them should go after Erwin, leaving the rest of their squad without any backup, or if he should go alone and risk not being able to find Furlan and Isabel again. Reflecting on everything that has happened since he first met Erwin, Levi announces that he will pursue Erwin alone, reminding them that he intends to kill Erwin himself. Isabel attempts to follow him, but Levi reminds her that Flagon and Sairam are much more likely to be devoured than he is, and that Isabel and Furlan will have a better chance of surviving with them. Furlan tries to convince Levi to wait out the storm, but Levi angrily reminds him that the Titans will not wait for the storm to pass, and that Furlan must trust him. Furlan laughs off Levi's statements and agrees, but demands that Levi make sure not to die, while Isabel demands that Levi return no matter what. Levi hesitates, then breaks away to pursue Erwin. Furlan and Isabel watch him go, then ride off to meet up with Flagon and Sairam.

Levi continues to ride, using his knowledge of the Survey Corps' formation to navigate his way to Erwin, inwardly ordering Erwin not to die until he arrives. In the thick fog, Levi momentarily pauses, but fails to notice the pack of Titans passing him, heading towards Furlan and Isabel's location...

Isabel and Furlan manage to find Flagon and Sairam. When questioned about Levi, they claim to have lost him in the fog. When Sairam suggests he was killed, Isabel angrily denies it, stating that Levi will definitely return.

Levi arrives at what remains of one of the Survey Corps' squads, having been massacred by the Titans. Levi identifies around four or five Titans from the footprints left behind, and becomes alarmed to see that they are headed in Furlan and Isabel's direction. Panicking, Levi begins riding back to them, knowing that they won't be able to defend against so many Titans at once. Levi catches a glimpse of the Titans in the distance.

Sairam is caught in the jaws of a Titan, and begs Flagon not to come any closer. He asks Flagon to take care of himself, before being completely devoured by the Titan.

Levi calls for Furlan and Isabel as he draws nearer.

Isabel watches as Sairam is devoured, and Furlan orders her to stay away, telling her that they won't be able to fight five Titans. He tries to suggest splitting up, but is suddenly attacked by a one of the Titans. His horse is startled by it, toppling over and pinning his leg.

Levi yells at his horse to hurry, but is forced to abandon it when its ankle breaks.

Isabel attempts to defend Furlan from the attacking Titan, slicing off its fingers before attacking its nape. She misses, and attempts to attack again, but slips on the Titan's rain-soaked skin. Disoriented, Isabel is left hanging from the Titan's neck. She opens her eyes to see another Titan approaching her. Terrified, she only has time to call for Levi before she is devoured.

Witnessing this, Levi is stunned, and angrily draws his sword as he continues to run to the battlefield.

Furlan sees the Titan that has devoured Isabel, its face covered in her blood, and draws his swords in a rage, but is shocked to see that his Vertical Maneuvering Equipment has broken. The Titan reaches for him, but is killed by Flagon. Flagon orders Furlan to find a horse, and is grabbed by the remaining Titan and devoured.

Levi finally arrives, witnessing Furlan attempt to fight off the remaining Titan. As the Titan pick up Furlan, Levi inwardly laments that everyone is going to die, realizing that his choice to leave them was wrong. Seeing Levi approaching, Furlan gives him a sad smile and waves. Levi attacks the Titan just as it bites down, killing Furlan.