Ji Soo Ho and Do Hyun Seo, who once dated for six years, meet again as a young rich CEO and a piano instructor who gave up on her dreams. Despite the awkward reunion, the two start piano lessons for their respective purposes. Meanwhile, talented musician, Kei, accepts Soo Ho's offer to work on a collaborative project and invites Hyun Seo as a fellow collaborator. Annoyed with this new partnership, Soo Ho proposes that they stay and work at his house, which causes subtle tension between the three. Soo Ho becomes confused after learning why Hyun Seo left him. Hyun Seo worries about Soo Ho's health, while Kei doesn't hide his feelings for Hyun Seo. Soo Ho and Hyun Seo embark on a bumpy romantic journey full of twists and turns. Will history repeat itself?