Melancholia

Ji Yoon-soo, math teacher, set to marry, assigned to prestigious Asung High School in Gangnam.

Yoon-Soo realizes that Seung-Yu is the one who guessed the math club's Calculus question.

When Yerin learns that Seung-yu used to be a math prodigy, she feels uneasy.

Seung-Yu and Yerin start preparing for the Math Olympics in earnest.

Seung-Yu opens up to Yoon-Soo about a past trauma she hasn't been able to tell anyone about.

Yoon-soo has mixed feelings about Seung-yoo's confession.

Four years later, Seung-yu has become a renowned mathematician.

Finally reunited with Yoon-Soo, Seung-Yu hovers by her side and tries to get closer.

Seung-yu tries to get Yoon-soo to come out of his shell, just like he did for her.

For the first time, Yoon-soo opens up to Seung-yu about her pain and hurt.

Thanks to Seung-yu, Yoon-soo finds a little bit of laughter, and the two share a special moment.

Seung-yu said that he was the subject of the Asung High School scandal and that it was a frame-up.

Seung-yu and Yoon-soo are finally able to reveal the truth about their past scandals.

Eventually, they realize that Sian has been victimized by corruption in the school.

The secrets of Aseong High School and Noh Jung-ah are finally revealed to the world.