Min Woo's first love was sadly unrealized. On one rainy summer day, he had fallen in love with Eun Hye, but unfortunately, she dies in a car accident. He runs into Hye Won in the mountains he used to frequent with his former flame, and sees that Hye Won and Eun Hye share many similar qualities. Hye Won had suffered a heart condition as a child and later underwent a heart transplant. She had received the heart from Min Woo's first love. When Hye Won first sets her eyes on Min Woo, her heart responded wildly. Jung Jae is Hye Won's childhood love who is gentle and handsome. But because Hye Won's heart continues to respond to Min Woo, she must choose which man to love.