Melancholia

Seung Yoo and Ye Rin prepare in earnest for the Math Olympics. Jung Ah and Min Jun teach Ye Rin the means to win, and Yoon Su finds out about the corruption in the competition. However, Yoon Su goes to Jeju Island with Seung Yoo to help him with the contest. On the same day, Ye Rin arrives at Jeju Island for internship activities for the competition.