First Casualty (慟哭, Dōkoku) is chapter twelve of the Akame ga Kill! Zero manga.
Summary
After finishing her fight with Cornelia, Taeko washes herself in a pond before returning to the town to search for Chelsea intending to get some backup from her. At the same time, Chelsea intending to assist Taeko, impersonates Guy only to be kidnaped by Guy's debtors much to her horror. As Taeko continues to look for Chelsea, she accidentally encounters Akame, realizing that this might be another good opportunity, Taeko proceeds to bait Akame to the location she killed Cornelia.
Akame initially not suspicious of Taeko follows her but eventually realized that she is being led on by Taeko. As Taeko shows Cornelia's location to Akame, Taeko tries to ambush Akame from behind. Akame, however, having realized that this was a trap counters in time. Akame proceeds to fight Taeko eventually overpowering her, proving herself to be more capable combatant than Cornelia. Before her death, Taeko admits that she and Cornelia were briefly until they became enemy as Akame lends the finishing blow.
Akame then goes to check on Cornelia only to realize that Cornelia is dead much to her despair. Meanwhile in the mountain, Najasho, Green and Guy are attacked by Babara who came to attack them, as the three struggles against the veteran assassin's strength.