After the monthly vote, Da Yeon meets So Ah and suspects that Harim did something with their votes. It seems like there is already some conflict in Harim's group. Meanwhile, there's also some tension in the relationship between Yerim and Eun Jeong because Yerim's priority now is to debut as a K-pop idol, so she has to keep a low profile. Soo Ji also understands that Ja Eun's approach of being nice to their classmates is better than manipulation, like how Harim does and how Soo Ji used to do. So, she forgives what Seung Yi and Ji Ae did and apologizes to Seung Yi in front of the class. When Harim arrives, Soo Ji proposes to everyone that since there is no Rank F student anymore, they should stop the game. Da Yeon and Woo Yi get agitated and attempt to hit Soo Ji, but she tells them to behave and asks everyone if they’re afraid of Harim and her group. They can let her know their decision through text. After that, Harim meets with Ye Won in private and asks Ye Won to reveal who voted for whom. Eun Byeol later shows up in the class. She has completely changed the way she looks and acts since she is now a Rank A student. She even orders Da Yeon and Do Ah to go buy her a drink. Soo Ji realizes that Eun Byeol has been Harin's wildcard all along, and she is right. Eun Byeol had approached Soo Ji in the beginning as Harim had instructed her, in exchange for exam answers. Soo Ji's group brings Yerim to the convenience store and introduces her to Seung Hwa. He realizes she is the girl in the photos all over his sister Woo Ri’s room. Soo Ji tells everyone that they should work together to break the perfect princess image of Harim. The next day, during cleaning time, when Harim and Eun Byeol are about to leave, Soo Ji stops them and asks them to clean as well. Eun Byeol claims that they are Rank A and don’t have to clean, but Soo Ji points out that Yerim is Rank A and is still cleaning like everyone else. Da Yeon shouts at Soo Ji, but Soo Ji isn't afraid and shuts her down. She tells Harim that it looks bad what she’s doing, trying to act superior to everyone. What happened starts to change people's views of Harim. Ye Won meets her and refuses to reveal the details of the votes. Harim throws her MacBook into a water bucket and transfers the same amount of money to Ye Won instantly while walking away. After school, Soo Ji learns that Ja Eun lives alone and has a broken sink. So, Soo Ji decides to go to Ja Eun's house to help her fix it. Soo Ji is very handy and fixes it right away. After that, they make noodles and rice cakes and eat together. Here, Soo Ji also learns that Ja Eun's mom lives in a small town in Busan. Her mom moved back there after Ja Eun's dad died and has to take care of the farm. Ja Eun thinks she will move back with her mom after graduation, but her mom actually wants her to become a civil worker. Meanwhile, Soo Ji wants to be a documentary filmmaker. Right at that moment, Harim texts Ha Eun's phone, and Soo Ji sees it. Soo Ji asks if Ja Eun has known for a long time, and Ja Eun reveals that Harim was in the same elementary school as her before moving away. They used to be close, and a flashback shows Harim bragging to Ja Eun about her parents but then asking Ja Eun to pay for the snack because she had already used all her money to get a new Nintendo, and Ja Eun nicely agreed.

In the present, Harim is upset that Ja Eun doesn’t listen to her order to get out of the house and goes to meet her. The next day, Soo Ji meets with Jae Hyeong and Yerim and asks them to help spread a rumor about Ja Eun. The rumor is that Ja Eun was a Rank F student because she was betrayed. In class, people start to notice Ja Eun and realize she’s a nice person with the personality of a big sister, and she receives more liking from the girls, which angers Harim. So, she goes to Ja Eun's mom's house. Meanwhile, Soo Ji's dad comes home and tells Soo Ji that he is being transferred and Soo Ji will have to move to another school next month. Soo Ji is surprised by the news and doesn’t know if the time she has left will be enough to break the pyramid game. She asks Yerim to go in front of the class to propose eliminating Rank A privileges since Rank F no longer exists. She also asks Da Yeon, Woo Yi, and Seol Ha to apologize to Ja Eun for beating her up, leaving bruises and violating the game's rules. When they try to deny it, Soo Ji says she witnessed them hitting Ja Eun brutally in the storeroom that day. Harim stares at Soo Ji and says that in the next ranking, there will for sure be a Rank F; if not, the ank A student privileges will be removed. That night, Ja Eun calls her mom, and her mom mentions that someone named So Woon has visited. Ja Eun is shocked to hear that news. For the next two days, Ja Eun doesn’t go to school. Soo Ji tries to call Ja Eun, but it doesn’t go through. She is more worried when Harim is absent as well. On the way home, Soo Ji sees one of her dad's superior and his wife taking out a lot of gift bags with the logo of Baekyeon Company from their car trunk. At home, Soo Ji realizes that the person who signed the transfer decision for her dad is also that superior. It turns out that he was bribed by Harin to transfer Soo Ji's dad so that Soo Ji couldn't stay to finish the plan with her friends. Soo Ji calls Harim, but Harim tells her she's busy and hangs up. Harim is actually outside Ja Eun's house. She asks Ja Eun if her mom knows why she bullied Ja Eun so much. Ja Eun admits that it was her fault. Then, suddenly, Harim uses a lighter to burn Ja Eun's hand. At that moment, Soo Ji shows up. She knows that Harim has used a lot of money and power just to bully them and tells Harim that she will not move schools and will stick with Ja Eun so that Harim can't bully Ja Eun anymore. Soo Ji swears to defeat both the game and Harim. The next day, Ja Eun finally goes to school. She tells Soo Ji that when the game is torn down, she will tell Soo Ji and their other friends a secret. A flashback shows that Soo Ji called her dad and asked to stay and graduate from Baekyeon High School, and her dad agreed. Before going to school, Ja Eun and Soo Ji go to the convenience store and meet Seung Hwa, who shows them a folder of audio recordings from Soo Ji's phone. The recordings are evidence of. Harim's group bullying, and Seung Hwa plans to publish them on a foreign YouTube channel. Seung Hwa is worried Soo Ji will have to deal with the same consequences his sister had to face, but Soo Ji isn't afraid. At school, Do Ah runs into Soo Ji, and the latter reveals that she accidentally mistook her phone for Do Ah's phone. But actually, she did it on purpose earlier that day to get the audio recordings of Harim's group bullying. After school, Soo Ji goes with her friends to the convenience store to listen to the audio recordings, but this time they couldn't get anything. The next day, they have a PE class. Eun Byeol suddenly shows up next to Soo Ji in the locker room and tells her to wait for the scary surprise they have prepared for her. In the PE class, for some reason, the teacher is absent again, and Eun Byeol steps up to explain a game that will be used for the final results. The rules of the game are so weird and absurd that a Rank D student with 1 vote will be hit with the ball by a Rank D student with 2 votes. Soo Ji realizes Harin is trying to replace a Rank F student with the four Rank D students that have 1 vote. She sends Yerim a text to tell her to change the rule as a Rank A student. Eun Byeol and Harim reluctantly agree to the new rule suggested by Yerim, that everyone should join the game and there will be 3 balls: one for Rank A, one for Ranks B and C, and one for Rank D. The more people one hits with the ball, the higher their score. The game soon becomes chaos when they start hitting each other crazily, eventually targeting Ji Ae and hitting her multiple times until Ja Eun steps in front to shield her. Soo Ji asks her group to take the balls and keep them still for a while. When Harim's group screams and forces them to continue the game, they go around and lightly tap the ball on their classmates and still score points, because in all these crazy rules, there is no rule stating they have to violently hit the ball on their classmates to earn a score. Everyone in the class regrets what they had done before and follows Soo Ji's group, making Harim's group, especially Da Yeon, who is always aggressive for no reason, look bad. After the class, even more people want to join Soo Ji's team. The four go to have lunch on the rooftop and have a quick nap there. Meanwhile, Harim calls Da Yeon's dad and tells him that Da Yeon messed up at school and asks him to scold her. Da Yeon is pissed but doesn’t dare to do anything. That evening, Harim catches Eun Jeong and Yerim in the class and tells them that she knows about their secret relationship and threatens to expose this information. Yerim tells Harim that she has powerful parents as well and isn't afraid of Harim's little game. However, Harim also knows Yerim's parents are against her debut as an idol and won't support her again if she fails to debut this time. Yerim tells Harim to do whatever she wants, but Eun Jeong is already on her knees, begging Harim to leave them alone. Meanwhile, Da Yeon is at home and is brutally beaten up by her dad while her mom ignores it. At Harim's house, her dad arrives home and looks at his daughter, who is on her phone conspiring something. He asks his wife whether they should send Harim abroad, but she reminds him that Harim has proof of his money laundering, so they can't do anything against her will. Mr. Baek wonders why his mom likes Harim so much, and Yi Hwa says it's because she's a psychopath and knows how to manipulate people. Meanwhile, Harim sends Soo Ji a picture of her dad shaking hands with Harim's grandma and asks if she still wants to upload the audio recordings. Soo Ji realizes that Do Ah knew her phone was swapped and informed Harim about Soo Ji's attempt to record their conversation. At that moment, Soo Ji sees her dad walk in with a document file from Baekyeon Corporation. It turns out Harim's grandma has contacted her dad and asked to do a charity project with him. On the other hand, Harim keeps texting Soo Ji, sending her an article and threatening to frame her dad as someone who uses his daughter to corrupt and climb the social ladder. Soo Ji goes to the convenience store and tells the seung hwa about what just happened. He tells her to delete the recording if she needs to, but Soo Ji still hesitates to do so.