Melancholia

At Asung High, Yoon Su’s new workplace, she gives a tricky question for students who want to join the math club. While no one in the class got the question right, a correct answer sheet is posted on the board outside the classroom. To find out who did it, Yoon Su provokes them and manages to find who it is.

Seung Yoo participates in the math competition and is picked to represent Asung High along with Ye Rin. The result shocks everyone who thought Seung Yoo had no talent in math except for Ye Rin who knows that Seung Yoo is a math genius. Meanwhile, the parents of other students and Ms. Noh aren’t happy with how Yoon Su runs her math class and club.

After the Math Olympics, Seung Yoo opens up and tells Yoon Su the traumatic experience he had bottled up inside of him for a long time. Yoon Su comforts him and sympathizes with Seung Yoos pain. However, Sung Jae witnesses the moment and gets overwhelmed with a strange feeling. Meanwhile, suspicions that Ye Rin got preferential consideration for the competition to become an issue.

After four years, Seung Yoo has now become a renowned mathematician, and he returns to look for traces of Yoon Su who has disappeared after the incident in 2017. Meanwhile, Principal Noh Jung Ah of Asung High School of Math and Arts proposes an offer to Seung Yoo, and Seung Yoo responds with another offer.

Seung Yoo tries to bring Yoon Su out into the world from her rut by getting close to her heart, just the way she helped him. Meanwhile, Yoon Su keeps her identity hidden while collecting evidence of Noh Jung Ahs corruption. However, when Yoon Sus identity is in danger of getting exposed, Seung Yoo stands in front of her.

Yoon Su starts to smile little by little thanks to Seung Yoo, and the two of them have an enjoyable and memorable time together. Meanwhile, Noh Jung Ah, who is furious at Yoon Su for targeting her, decides to get in the way of Si An, the one student Yoon Su cherishes. Yoon Su notices the provocation and resolves to face her.

Seung Yoo understands the error in the premise and Yoon Su deeply. He becomes frustrated because his love for Yoon Su obstructs any means of proving Yoon Sus innocence. To comfort him, Yoon Su takes him to a place of warmth and healing. They escape the peoples attention and prejudice as they spend time together. Meanwhile, Noh Jung Ah gets faced with a crisis from every direction.

Yoon Su and Seung Yoo hold hands for Si An, supporting, relying on, and moving together. In the end, they get close to exposing that Si Ans condition was the cause of what went behind the Global Talent Class, the special textbook, and the corruption at Asung Academy. And to destroy Noh Jung Ahs Asung kingdom, Yoon Su and Seung Yoo begin to persuade people to tell the truth.