Soundtrack #1 (Season 1): Two people have been friends for two decades, but just two weeks of living together erase the fine line between love and friendship. Han Sung Woo is a handsome novice photographer with a kind and caring character, and Seo Eun Soo is a lively, straightforward and honest girl who openly expresses her feelings. Three years ago, she took the chance to become a lyricist. Now the details of their related romance are subtly woven into her musical compositions.

Soundtrack #2 (Season 2): Suho and Hyunseo, who once dated for six years, meet again as a youthful rich CEO and a piano instructor. K works with Suho on a collaborative project and invites Hyeonseo to join them. Suho and Hyunseo embark on a bumpy romantic journey full of twists and turns. Will history repeat itself?

Each season features a new storyline with different main cast.