Blueming

Cha Si Won narrates how he was teased for being chubby as a child and ridiculed for having a father who abandoned his family. He develops a sense of resentment towards Da Un for his natural charisma, but to his dismay, gets paired with him for every group activity. After a party, a drunk Cha Si Won blurts out his honest feelings to Da Un.

Si Won wakes up on Da Un's bed after Da Un decides to take him to his own home as he was intoxicated and unconscious. He leaves embarassed and attempts to avoid him at the University. Da Un, nevertheless, tries his best to get him to talk. Following a half -hearted conversation with him, Si Won accidentally bumps into a painting by Yun Jeong, freshman of his same major. They formally get to know each other. Da Un decides on a date for their joint assignment and Si Won agrees.

Si Won and Da Un decide to visit a book cafe, but they flee the spot after Si Won runs into his father with another woman. He rides a bike to cool himself off, leaving Da Un behind after he falls off his bike. Si Won returns and apologizes for his insensitive behaviour. Da Un clears up any misunderstandings regarding his actions to Si Won. He gives a 'covered kiss' to him, leaving Si Won confused.

Da Un follows Si Won to his home and they run into Si Won's mother and sister, who invite Da Un over for dinner. He stays over at his place that night and reveals that it was his birthday. Si Won asks him why he never told anyone, but Da Un insists that he had a great day, requesting the permission to hang out at his home as his birthday gift. The two of them overcome their differences and starts to grow closer. Si Won's scenario is unexpectedly selected as the winner of a contest in which he had insisted that he would not participate, leading him to get labelled as a backstabber by his friends and seniors. Moreover, he comes to know about Da Un's parents' involvment in it.

Si Won finds out that his sister had submitted his work. He becomes the subject of rumour and ridicule and a chubby childhood photo of his is circulated around. He asks whether Da Un (whose parents were the owners of the production company that held the contest) had had a hand in making him win. He loses control and snaps at Da Un when he tries to comfort him. He, nevertheless, takes Si Won's bike back home for him. Si Won goes to Da Un's home and has a heart to heart talk with him. He finally speaks out about his insecurities and reveals that he knew that Da Un likes him.

Yun Jeong and Do Ba Wu find out that Seonghwan Sunbae was the one who spread Si Won's childhood pictures around and warn him against doing it again. Si Won lacks confidence in his scenario, but moves forward and shares it with his classmates. Da Un steps on Seonghwan's phone after he derides Si Won. Yu Jin, Yun Jeong's friend, visits Si Won to apologize as his picture had been initially used by her as a proof to prove that they used to attend the same Elementary School. They part on friendly terms.

Si Won and his classmates start pre-production of the movie. He struggles to find inspiration for his script and Da Un suggests heading to a hotel to clear his head. He takes him to a sea side hotel where he had once gone alone. Si Won opens up about his lack of confidence. He asks Da Un about himself, but when he brushes off his troubles as silly, Si Won advices him against repressing his pain.

Si Won and Da Un spent a night at the hotel. The official production of Si Won's movie begins. The first screening of the movie takes place and Da Un's mother, an award winning director, who had provided the funds for Si Won's winning script invites him and Da Un over for lunch. While he goes out for a moment, he overhears her talking to Da Un about how she had selected Si Won's scenario plainly due to Da Un's insistence and that it would never have made it to the screens if it had not been for him.

Si Won is immensely hurt by the fact that Da Un had sat back and let it all happen, pretending to not know anything. He walks away from him. Returning home he finds his mother in tears after she watches his movie on his laptop. She claims that everything she did was for him. Si Won doesn't argue, but tearfully apologizes to her. Yun Jeong and Cha Si Yeong, Si Won's sister, become closer than mere acquaintances. Da Un attempts to apologize for his actions.

Da Un fails to properly convey his emotions. Si Won sends him a message asking whether things between them were over for real. Da Un, distraught, dreams of his family spending time with him, Si Won's parents getting together and Si Won reconciling with him. The next day, he visits Si Won and expresses his sincere apology, but worries whether it's too late. Si Won gives in and forgives him, finally reconciling for real. They once again spend their day at the sea side hotel, learning more about each other.