Su-ji, a new student at Baekyeon Girls' High School, gets voted to the bottom of the hierarchy in her class through the Pyramid Game and makes a plan to rise to the top.

Su-ji tries to find the mastermind of the Pyramid Game and teams up with her classmates who suffer from the game.

Su-ji receives much better treatment from her classmates after she gets moved up to Grade C. Su-ji, Ja-eun, and Ji-ae devise a plan to end the hierarchy game.

Ja-eun tries to befriend Jae-hyung to recruit her into the team. Su-ji confronts Hae-jun about betraying her friends.

Seung-yi makes a scene expressing her distress in the classroom and blames Su-ji; during the parents' visit, Ha-rin's presentation surprises everyone.

Su-ji convinces Ye-rim to carry out the plan to get rid of Grade A's privileges and stop violence in the classroom; Ha-rin devises a plan to counter Su-ji's efforts.