Hee-jin and her friends find out that Jae-yeol and Yeo-reum were a couple a few years ago. Hee-jin doesn't show it to others, but she's bothered by it. Jae-yeol tells Hee-jin that there's nothing between him and Yeo-reum, and this makes Hee-jin relieved. Watching them, Ji-won gets confused about his feelings toward Hee-jin. Meanwhile, Yeo-reum comes to school to see Jae-yeol again.

Multiple misunderstandings build up between Hee-jin, Jae-yeol, and Ji-won, causing Hee-jin to believe that Jae-yeol still has feelings for his ex, Yeo-reum. Meanwhile, the campus bustles as the school festival approaches with the Confession Tree event, planned to be hosted by Yeo-reum.

Jae-yeol and Ji-won's war of nerves escalates after the incident of the Confession Tree. While Jae-yeol is tormented between Hee-jin and Yeo-reum, he finds out about the truth behind his breakup with Yeo-reum. Hee-jin and Ji-won keep running into Jae-yeol and Yeo-reum, and they end up sharing a meal together at the same table.