Chapter 24

Retaliation Time (仕返しの時間, Shikaeshi no jikan) is chapter 24 of the Ansatsu Kyōshitsu manga.

Long summary
Seo and Kaho are having coffee in a cafe, sheltered from the rain. Seo compliments Kaho on her choice of shops, to which Kaho notes the cafe is managed by one of her dad's friends. Seo asks if she ever came to the cafe with Maehara. Kaho immediately denies this and apologizes for hanging out with her old boyfriend yesterday. Seo reminds her not to hang out with people that fall into Class E. He then reflects on their superiority from sitting in a shaded area of an open-air cafe, unlike a certain someone.

An elder couple approaches the two, asking for Seo to pull his leg back so they can sit further in. Grudgingly, Seo complies and the couple thanks him as they walk through slowly. As they sit down, Seo insults the couple out loud for being old.

Looking through binoculars from a nearby house, Tomohito Sugino is fascinated that the elderly couple is actually Nagisa Shiota and Kaede Kayano in disguise. Next to them, Sōsuke Sugaya explains that he used party masks and revamped them, to which Sugino compliments his work. Recalling one of his failed disguises as a middle-aged man, Sugaya reflects he still needs to work on them to fool Korosensei. He then claims his disguises are good enough anyways because Kaho and Seo are uninterested in people who appear weak. The two then reflect on how they were able to use the house right across the cafe thanks to Tōka Yada and Hinano Kurahashi, who are now entertaining the landlord with skills they learned from Bitch-sensei. Korosensei emerges inside a darkened room filled with class 3-E students, including Sugino and Sugaya, and commands them to commence the operation. From outside, Manami Okuda emerges to give Korosensei the custom bullets he requested. Okuda claims she has them, but had trouble getting them into the shape of BB pellets. As the students with the best marksmanship in the class by gender, Ryūnosuke Chiba and Rinka Hayami load Okuda's bullets into their sniper rifles. Sugino sends a text message to Nagisa signalling that they're all set to go.

Eyeing each other, Kaede Kayano asks Nagisa Shiota if there's a restroom around the area and recalls there being one in a convenience store 100 meters back. Nagisa points out the cafe washroom to her. As Kayano enters the washroom, Kaho laments on how awful senility is. Suddenly, Nagisa knocks over his salad and water, prompting Seo and Kaho to look over at him. From the windows of the house across the street, Chiba and Hayami successfully fire their BB pellets at their coffees. Hayami claims that shooting it in their coffees is easy compared to hitting a target moving at Mach 20. Seo and Kaho yell at Nagisa in disguise for being loud, to which Nagisa apologizes and offers to leave once his companion returns from the restroom. Seo expresses his disappointment for the low-grade customers today, to which Kaho apologizes, claiming the patrons are usually smarter. As Sugino types on his phone, Korosensei eats a mug and laughs as the rest of the students take on their roles.

Suddenly, Seo and Kaho's stomachs start to hurt. Seo suggests that something may be wrong with the coffee, to which Kaho feels is an insult about her favorite place. Okuda explains that she mixed the BB pellets with magnesium as the main ingredient, creating a powerful laxative causing bowel irritation stronger than over-the-counter drugs. Sugino looks at her funny as she laughs and calls the laxatives Victoria Falls. In the cafe, Kaho and Seo rush to the restroom only to find its door locked. Only then do they realize the bathroom is already occupied by the hag from earlier. Ignoring their knocking inside, Kayano is sitting on the toilet with her disguise off, folding origami paper cranes and thinking of going to a thousand. Seo and Kaho then ask the manager for another bathroom. With his tie held by Seo, the manager mentions another one in the area, the convenience store about 100 meters away, as Kayano had mentioned earlier. Seo takes his umbrella and dashes away from the cashier. Catching up to him, Kaho is frustrated that they need to go together and tells Seo to go elsewhere since he's a boy, to which Seo refuses. From a tree above with two others, Hiroto Maehara watched the two running over and reflect on how they have too much pride to ask to use a bathroom in a private house. Alongside Yūma Isogai and Hinata Okano, the three of them cut the branches off the tree, sending a pile collapsing over Kaho and Seo. Kaho is disgusted from getting all wet and finds a caterpillar. Feeling immense pain, Seo makes a distressed face and dashes for the toilet again. From the tree, Okano reflects on how the two don't have any time to figure out the situation, while a shopkeeper from below thanks the children for cutting down the branches and praises them for their skill. Isogai cuts himself off from crediting to the shopkeeper their special ambush training to tree climbing training. All the students meet up with Korosensei as they watch Kaho and Seo grabbing each other and fighting over using the convenience store bathroom in humiliation, with an employee rushing to stop them.

Maehara stumbles to thank everyone as they give him smiles identical to Korosensei's. Korosensei approaches Maehara and asks him what's wrong and if he still believes he's the kind of person who'd calmly torment the weak. Maehara reflects it'd be impossible for him now after watching everyone. He claims everyone doesn't look strong, but they possess many hidden weapons they can rely on in which he doesn't have. Korosensei affirms him by adding that sight alone cannot determine strength and weakness and that he'll have a hard time looking down on the weak in the future. Maehara smiles back and agrees. He suddenly realizes he has a dinner date with a girl from another school and quickly thanks everyone and waves goodbye. Everyone is left with a poker face identical to Korosensei's.