Kill the Colossal Danger Beast (巨大危険種を斬る, Kyodai Kikenshu o Kiru) is chapter 26 of the Akame ga Kill! manga.
Lubbock gets a response from his barrier and learns of an intruder at the base of the mountain. He sees there is only one person but the speed of the person isn't ordinary at all. The mysterious person comments as he moves that the Danger Beasts (which he calls Dr. Stylish's posthumous mementos) in the mountains are all gone, so he starts climbing the mountain. Lubbock learns he is climbing the mountain but decides to hide and let him pass, as he didn't want to fight someone of that caliber. However, he then realizes Tatsumi hasn't come down from the mountain yet, which causes him to become suspicious.
Up on the mountain top, Esdeath lovingly embraces Tatsumi after confirming it really is him and wondering why he ran away from her. Tatsumi nervously asks why she is up in the mountains and she explains was on night patrol exterminating the Danger Beasts threatening the Capital. She then asks what he is doing in the mountains himself and Tatsumi gets nervous about how he will respond. He does ask she let go of him because she is pressing the back of his head into her breasts, which is making him uncomfortable, but she refuses, not wanting him to run from her again. He breaks free and says that he came out to the mountains to test his abilities and fight the Danger Beasts; an answer Esdeath accepts. She asks him if he got into the Revolutionary Army but he says he hasn't, though he doesn't plan on changing his mind so he has been training himself. Esdeath notices he has gotten stronger since she last saw him and praises him, and while Tatsumi is flattered, he reminds himself to keep his head in the game. Esdeath admits she destroyed a good number of Danger Beasts in the vicinity, and while she found them annoying, she was glad they brought her to him as she nuzzles his face. Tatsumi, on the other hand, is worried he won't be able to escape her again and wonders if he should fight her, but decides against it because of how strong she is. As Esdeath admires how cute he looks when he is thinking, she senses someone's presence and draws her sword on a rock, telling whoever was hiding behind it to step out.
Sure enough, the cloaked figure appears and commends Esdeath for discovering him, as he thought he hid pretty well, but now that he has run into her, playtime is over. Esdeath informs the man she will take him to the torture room for interrogation, but the man instead tells her he wants her to do some clean up for him. He then pulls out a pendant-shaped Teigu called Shambhala and calls out its name, which activates a symbol underneath Esdeath and Tatsumi that warps them away. Afterwards, the man takes off his cloak, revealing his face, and says that it is too early to report his return to the Prime Minister, so he should find a new toy to play with.
The teleportation reveals that the two of them were now on an island; a revelation that leaves Tatsumi completely dumbfounded. He asks Esdeath to hit him quickly and with no wounds, and Esdeath becomes excited, as she believes he has masochistic interests, which would be a perfect match for a sadist like herself. Tatsumi denies this and says that it may be possible they are under an illusion the man casted, so perhaps some pain may wake them up. While Esdeath understands the logic, she instead gives Tatsumi a kiss. Afterwards, Esdeath realizes they aren't under an illusion because the sensations she feels from both the kiss and the environment are all real, which means they were definitely warped to another location. Tatsumi asks if that is possible and Esdeath reveals that some Teigu she has heard of could do spatial manipulation, though it seems rather rare, so she wonders just who exactly was the man they encountered.
Nevertheless, Esdeath decides to gather their bearings and creates a huge pillar of ice that raises the both of them far above the horizon, where Tatsumi sees nothing but ocean and deduces they are indeed on an island. Esdeath then says that with the pretty surroundings, it is almost like the two of them are on a date, which causes Tatsumi to comment how calm she is, and she says it is because she has an open mind with how to use her Teigu. She embraces him once again saying they are on a date, but the two are then surprised by the presence of a colossal Danger Beast. Tatsumi looks closely at it and realizes it resembles Dr. Stylish after he transformed, and remembered how it took all of Night Raid to take it down. As he wonders how just the two of them can take it down, Esdeath forms several icicle shards and fires them at the Danger Beast, calling it a mere hindrance. Tatsumi is left stunned by this display of power and wonders what exactly her Teigu is called.
The Danger Beast gets back up as Tatsumi points out its weak spot, which Esdeath also noticed and says the two of them really are meant for one another. She creates a horizontal pillar of ice and fires it at the Danger Beast, but its weak point dodges. Tatsumi, however, runs on the pillar to the weak spot and slays it. Esdeath is left even more charmed by him despite hoping to show off her skills and one of her special moves. Her ice pillar is then tackled by another large Danger Beast, but she destroys it by dropping a huge block of ice on it. Tatsumi is left even more shocked by Esdeath's strength, and wonders how exactly Akame will kill her.
After destroying the Danger Beasts, Tatsumi is eating food while Esdeath writes stuff down in her notebook while saying that the island is a place to hide new types of Danger Beasts. He asks what they should down after they finish resting, and she says that should investigate their surroundings while keeping a cool head. Tatsumi earnestly responds before remembering Esdeath is his enemy and walks off, as it is revealed Esdeath was sketching Tatsumi in her notebook along with a sketch of her with him. She then notes the sketch doesn't resemble him though. Eventually, the two of them go around the island eating food and exploring the wildlife. Esdeath even takes off her shirt in front of Tatsumi while smiling happily.
Night falls as Tatsumi notices it happened while they explored, but Esdeath says it was fun. She then reveals they are on an uninhabited island far to the southeast of the Empire, which she deduces after observing the flora and fauna on the island which she read about being in the southeast and the position of the stars, which surprises Tatsumi. Esdeath says that she and him are the only ones on the island, so she offers him three choices on one he will do; 1. Live here with her for a while, 2. Return to the Capital together and live there, and 3. Holding her. Tatsumi says none of those are choices for him, which bums her at how un-cooperative he is. Tatsumi asks why she is so composed, and she explains she has an idea on how to return, but she will need his help, which he agrees to. He gets a bad feeling about what will happen, but he decides to bet on running away admist the confusion.