Kill the Little Sister (Part 1) (妹を斬る (前編), Imōto o Kiru (Zenpen)) is chapter 64 of the Akame ga Kill! manga.
The morning after the battle with the Dark Squad, Tatsumi complains about how he missed the fight by the time he woke up. Leone tells him that even if he had woken up, they would have left him behind, with Najenda adding that he is not to engage in combat until the war begins. Tatsumi tells them that he feels bad everyone else is fighting hard out there while he is just relaxing, but Najenda pats him on the head and reaffirms him that when the fighting starts, they will work him good and proper. Leone teasingly shoves Tatsumi into her breasts while suggesting a hidden context to 'working' him. Akame sits up and says that Tatsumi played a huge role in their efforts at the execution grounds so it is only natural he still be recovering, and leaves after thanking them for the food. Tatsumi and Leone look at her worriedly.
In the main room, Tatsumi comments how quieter than usual Akame has been, and Leone says it is because she is meeting Kurome tonight. Tatsumi looks to Najenda and asks if she is doing this with her approval, and Najenda responds by saying that since Kurome was their original target, removing her from the Empire will reduce their ability to assassinate their key players. Najenda then says to Tatsumi that she doesn't actually think Kurome's presence in the actual battle will be a defining factor in victory or defeat. It is just she doesn't want their supreme commander to die, so they are forcing this this situation to happen. When Tatsumi inquires why, Najenda reveals that when Akame first joined the Revolutionary Army, she had conditions: she would be allowed to act according to her own discretion regarding anything involving her sister. Najenda believes it is time for her to honor that request and as such did so. Tatsumi asks Leone what she will do and Leone says that she will let Akame do what she wants, whether she decides to kill or save Kurome, but she will do everything she can to help her. Najenda adds that in the case the Empire falls and Kurome is spared, the Revolutionary Army will not charge her for her crimes and Akame will be responsible for looking over her; something she approved of last night as it also fell under Akame's conditions, and that she has worked hard all this time to ensure her requests are met. Tatsumi realizes that Akame isn't going to battle, it is just a one-on-one confrontation with Kurome. Najenda says that this will help Akame remove sides from the equation and make it just the two of them, which will also give herself a chance to find a way to finish her without killing her. Leone says to Tatsumi that if Kurome is saved instead, it will just mean she won't be a member of the Imperial Army. She does tell him to go into this situation assuming Kurome would refuse any type of aid and that killing her will be the only option, and that if Akame could have persuaded her that easily, this confrontation wouldn't be happening, so all they can do is support her no matter the outcome. Tatsumi continues to think, and Leone asks if he wants revenge for Chelsea, but he says that isn't it. He agrees with the two of them that he will help Akame no matter the outcome of their confrontation. This surprises the two of them, as Najenda thinks back to when she first met him and how the old him would have tried to prevent this from happening. She doesn't see it as maturing though, and wishes desperately to bring this horrible era to an end.
Outside, Tatsumi finds Akame sitting up against a tree and asking her if she should be getting some rest. Akame admits the night has made her restless, and Tatsumi reveals to her that he plans on joining her. Akame refuses his help because this is just between her and Kurome, but Tatsumi explains that he is her friend, so he will still help her. Akame reminds him that she told Kurome she would come alone, and Tatsumi says that he wouldn't interfere with their conflict. He then proposes the idea that Kurome may not come alone either, so he wants to eliminate any third party to ensure they have their fight. This touches Akame, though she says she remembered Najenda telling him not to fight until the war, but Tatsumi said it was only because she was concerned about him after seeing his condition the last time he used Incursio. And while he remembers what the doctor told him, he says he would willingly use Incursio tonight if he felt he had to, because he didn't want to be left behind. Though Akame is unresponsive, Tatsumi reminds her that he doesn't intend to exceed his limit because he wants to return to Mine, but he can't just sit by looking after himself while he still has strength to fight and his friends get hurt. Akame thanks Tatsumi for his kindness, before standing up and reminding Tatsumi that Murasame has an ultimate technique that she can't use yet. She then explains that in order for her to use it, she needs to discard her humanity, and it may soon be time; this revelation shocks Tatsumi. She explains to Tatsumi that Wave told her she was insane if she thought killing her sister would be saving her, and that perhaps he is right since she can wield Murasame the way she can. She admits she will try to reason with her before asking Tatsumi to kill her should she embrace the demon inside her heart and become possessed by Murasame, as she would consider it an honor. Tatsumi agrees, but only if she kill him should he be overtaken by Tyrant, as that would be an honor for him as well. This surprises Akame, and Tatsumi says that she is probably thinking he is being cowardly because he still has Mine, and while the old him would have agreed, he reminded her that she made him promise he wouldn't die. Akame apologizes and agrees to give it everything they have together.
Back in the Capital, the supervisor of the Dark Squad yells at the remaining members of the Dark Squad, including Kurome, for failing to kill anyone. He yells he will hold them accountable for this failure, only to be surprised by Esdeath's arrival, who says that someone will indeed be held responsible for what happened. Just as he thought she would help him bring them to the torture chamber, Esdeath kicks the man's head so hard it literally spins off his body, resulting in his death. Esdeath then revealed she was punishing the 'senile old fool' for ordered a suicide mission that had zero chance of success. Esdeath admits she hadn't realized the Dark Squad was lacking in leadership, which no doubt made their jobs very tough. As such, she declares she will be their new supervisor and inform the Minister, and until the war, they are free to do as they please.
Kurome returns to Wave's room and informs him of the mission's failure, though she admits she wanted to still succeed though, because she felt if she came through, she could have been acknowledged. Wave then picks up Kurome and carries her to his bed where he lays her down. Kurome prepared herself for something intimate to happen, only to be surprised when Wave pulls the covers over her and tells her to get some sleep while not worrying about the negative aspects of what happened. Kurome says she can't so Wave offers to sing a lullaby he heard in his home village, though he admits it won't sound good since he can't sing. Nevertheless, he pats her head and says that he will cheer her up. However, after he pulls his hand away, he looks down and realizes he pulled out some of her hair by accident, which horrifies him. Kurome notices this and sadly says she has run out of time, but Wave yells that she shouldn't talk like that. He declares he will get her to quit the Dark Squad after the war, get her off those drugs, and find her a viable treatment to increase her lifespan. He also yells that he will beat the hell out of anyone who stands against him, believing the merits and medals he may earn from the war will ensure her protection. Kurome tells him that she has lived this long to fight, and if she gets off the drugs her commander will discard her as a battle asset. Wave denies this, believing she is already strong without them, and if her commander tries to remove her from military service, he will get himself promoted until he can become her commanding officer himself, so she can get off the drugs. Wave desperately asks her to find another reason to live, but Kurome sits up and says she can't see herself serving him. Wave tries to justify this by saying he would let her eat whatever whenever and he would ignore whatever she would do. Kurome adds to this by saying that Akame could cook something, but most likely would blow it up, so she could just be her aid, Natala could handle the cleaning, and Run could take care of books; these statements disturb Wave. Kurome reveals to Wave that Akame called her out for a one-on-one match and that she plans to kill her and add her to her corpse collection. As she gets up and proceeds to leave the room, Wave beats her to the door and tells her he won't let her, despite her insistance. Wave declares that he is her friend which is why he is stopping her, and if she does go she will notify the commander and they will leave together, because he will protect her. Appearing touched by this, Kurome kisses Wave, but then punches him in the gut and knocks him down. She tells him before he passes out that as far as Akame is concered, she needs to do as she pleases.
Kurome leaves Wave's room and runs to hers to get Yatsufusa. She dons her coat and heads out.