Sol had gotten into an accident and had no will to live a life. However, a phone call from Sun Jae, the vocalist of the group Eclipse, gave her hope and comfort. Since that day, she has become Sun Jae's fan. Years have passed, and Sol goes to Sun Jae's concert. But a few hours later, Sun Jae is found dead. And then, Sol goes back to 2008, when Sun Jae was still alive.

Sol is confused about the situation, but one thing she knows is that she must save Sun Jae. She finds out that she can't directly explain the future. To save Sun Jae, she decides to become friends with him, but it's not easy to become friends. Meanwhile, Tae Sung is curious about Sol who changed all of a sudden. And Sun Jae is also bothered by Sol who appeared in front of him from nowhere.

Sun Jae wins the gold medal at the competition, and he decides to confess his feelings for Sol. But due to unexpected events, it’s not as easy as it seemed. Sol thinks that she has changed the future, but Sun Jae gets hurt during practice. Sun Jae decides to quit swimming, and it makes Sol heartbroken. Sol tries to comfort Sun Jae, and Sun Jae finally confesses his feelings for her.

Sol is back in 2023. She couldn’t save Sun Jae, but she found out that she did make some changes in the past. She manages to go back in time again, but things have turned out strangely while she was gone. Sol is officially dating Tae Seong, and Sun Jae feels confused and betrayed about Sol. He wants to keep a distance from Sol, but Sol keeps showing up. Meanwhile, Sol gets lost on her way home.

Sun Jae saves Sol just in time. Sol realizes how precious her life is and tries not to miss out on many things. Tae Seong feels jealous of Sun Jae who seems close to Sol. Meanwhile, the vocalist of Tae Seong's band can't come to the band contest, and Sun Jae sings for the band. Sun Jae gives the prize to Sol as a gift, but Sol is upset because he sang in a band which she wanted to prevent from happening.

Sol breaks up with Tae Seong, thinking he only dated her to avoid the girl who likes him. Sun Jae tries to be cool with Sol so he can win her heart, but it’s not easy for him to hide his feelings. Sol tries to avoid her accident that will happen to her in the future. Meanwhile, Tae Seong gets in an accident and gets hospitalized. At the hospital, he runs into someone unexpected.

Sol manages to escape from the kidnapper, and Sun Jae saves him. At that moment, Sol is back in 2023. She is relieved to know that Sun Jae is safe as well, but a lot of things have changed. Her legs are fine, and she works at a film production company. Hyun Ju and Geum are married and having another baby. Meanwhile, Sol goes to Sun Jae’s concert to meet him.

Sol and Sun Jae meet at the Hangang Bridge as they promised. Sol is worried that something might happen to Sun Jae if she lets him go. She insists they spend the night together, and the two end up going to Sun Jae’s place. They finally realized how they felt about each other after all those years. However, an unexpected accident happens, making Sol flustered again.

Sun Jae is attacked again, and he’s in a critical condition. Police disclose information on the culprit, and Sol notices that the timeline has changed again. She manages to find a way to get back to the past, and this time, she goes to the same college with Sun Jae. Sol wants to keep distance from Sun Jae, but they keep run into each other. Meanwhile, Sun Jae gets a chance to get a rehabilitation training in the US.

Sun Jae tells Sol he will leave for the US for the rehabilitation training. Sol is relieved to hear the news as he’ll be safe in the US, but she feels sad at the same time. In Hyuk asks Sun Jae to join his band and go to the audition together. Tae Seong finds out about Sol’s kidnapping case, and he comes to see her. Meanwhile, Sun Jae goes to the airport to leave for the US.