Crushology 101

When it comes to dating, Bunny cares about looks. Having high standards for men, however, good-looking guys have no interest in her. Therefore, she ignores her boyfriend, Bong-soo's looks. Meanwhile, Bong-soo makes a big mistake and humiliates Bunny. Bunny was going to take a leave of absence, but she changed her mind immediately after bumping into a good-looking guy.

Bunny is determined to pay back her debt of 2,000 dollars. However, she lacks the means to do so and decides to work part-time at an exhibition. There, she meets another handsome guy. Bunny also decides to enter a strength contest to win a brand-new tablet and be freed from her debt and notetaking.

A-rang agrees to do the alumni interview as Hee-jin asked him to. Seeing Hee-jin getting closer with A-rang, without knowing, Jae-yeol is concerned about Hee-jin and tells Hee-jin that A-rang isn't a nice guy. Meanwhile, A-rang wants to see Hee-jin in private, and he invites her to his studio.

After checking the conversation between A-rang and Ji-young, Jae-yeol runs to Hee-jin, worrying that she would be fooled by bad guys again. However, Hee-jin thinks what Jae-yeol does is cross the line and doesn't listen to him. Out of concern, Jae-yeol asks Ji-won for help. Meanwhile, Hee-jin finally gets to see the real side of A-rang.

Hee-jin tells Jae-yeol what happened that night, thinking he would be embarrassed about it. However, Jae-yeol doesn't get startled by it, and he confesses his feelings again. Hee-jin is still in doubt, but unexpected events make her think about him again. Meanwhile, Yeo-reum, who is a popular sports announcer, comes to school, and it seems like she and Jae-yeol have a history.

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.

Just as Hee-jin and Jae-yeol find happiness, disaster strikes Hee-jin's family finances and her crucial art project is jeopardized. Reeling from setbacks and leaning on Ji-won for support, she unknowingly fuels Jae-yeol's suspicions. Their fairytale beginning crashes hard against grim reality.

While Jae-yeol's suspicions grow, Hee-jin applies for a scholarship program in the US. Things become more uncomfortable with the realization that the two must stay apart if she is accepted. On top of that, Ji-won also decides to go to the US to stay with his parents and sister.

Hee-jin comes back to Korea after a year in the US. As she returns to school, she encounters Jae-yeol, her ex. Meanwhile, she also runs into Hyun-o, her first crush from when she was little. As the three coincidentally keep bumping into each other, a whirlwind of emotions ensues.

Jae-yeol wants to tell Hee-jin how he feels about her, but Hee-jin ends up misunderstanding his true intention. Hyun-o asks out Hee-jin, and it makes her even more confused. Meanwhile, Jae-yeol finds out that he lost the hard drive that has all the work of his commercial footage. Hee-jin ends up helping Jae-yeol find the hard drive, and Jae-yeol finds another chance to confess his feelings.