Do-hyun, the captain of the basketball team, is preparing for the basketball championship. In 5 on 5 game, when a teammate gets injured and one spot is empty, Hye-in, the team manager, brings someone who has a strong build. The man Hye-in brings is Dong-wook, Do-hyun's first love who didn't work out... 5 years ago, Dong-wook and Do-hyun was in the same highschool. Dong-wook has suffered from chronic insomnia every night and it has gotten worse with the bad weather. One day in those painful days, he fell into a deep sleep next to Do-hyun by chance. That’s how Do-hyun, has become the only shelter for Dong-wook. The two of them spent time together in the gym, gradually became closer, and eventually they kissed. However, due to his father's business, Dong-wook had to transfer schools. He couldn't confess his feelings to Do-hyun after witnessing Do-hyun playing around with his classmate, so he left, causing nothing but pain to Do-hyun. However, their relationship, started with first love and ended in misunderstandings, continues again after facing each other on campus. Do-hyun opposes the idea of letting Dong-wook play in the game, but he has no choice but to play with him in the upcoming match. Instead, they make a bet between themselves. Dong-wook leads the team to victory, and he officially joins the basketball club. After winning the bet, Dong-wook suggests to Do-hyun that they live together, and they end up as Dong-wook wants...! Do-hyun, who is shaken by Dongwook's straightforwardness, and Dong-wook, who can only fall into a deep sleep when he is with Do-hyun, who has trouble sleeping at night when they are together. Will they be able to reconnect their broken ties?...