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-sung 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-sung feels jealous of Sun-jae who seems close to Sol. Meanwhile, the vocalist of Tae-sung'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-sung, 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-sung 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-joo 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-sung 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.

Sol and Sun-jae decide to be honest with their feelings and enjoy every moment together until Sol goes back to the future. Their parents find out that they are dating, and a small mistake leads to a big misunderstanding. Kim Young-soo is arrested by the police and Sol feels relieved. Meanwhile, In-hyuk's band is performing for the last time and tries to help him.

Kim Young-soo escapes and Sun-jae wants to protect Sol and make her feel relieved. They run into Geum and Hyun-joo and find out about their relationship. In-hyuk goes back to his home in the countryside as he quits the band. Sun-jae, Sol, and Tae-sung go to In-hyuk’s place to tell him that Eclipse might have a chance to debut. Meanwhile, Sol notices that the future has changed.

Sol lies to Sun-jae and leaves him. Sun-jae comes back to Seoul alone, but he finds out that Sol lied to him. He goes back to find her, but Sol doesn't answer his calls. Meanwhile, Sol asks Detective Kim to help her catch Kim Young-soo. Since she knows when and where the incident will happen, she sets a trap to get him at once. However, the incident brings an unexpected result.

After Sun-jae and Sol's brief and misunderstood encounter at the award ceremony, Sun-jae is accidentally given the wrong script proposed by Sol. However, upon reading it, Sun-jae becomes inexplicably determined to play a role in it while Sol tries her best not to get mixed up with him. But as things don't go the way she wants them to, Sol even thinks about quitting her job.

Sun-jae's memory comes back and now he remembers everything that happened between Sol and him. Thanks to Tae-sung, the ill-fated relations are resolved and the couple can be together. Sun-jae wants to propose to Sol, but finding the right time is difficult. Sun-ae decides to attend Sol’s nephew’s first birthday party and meet Sol’s family.