A world where you're born with five luminous hearts on the inside of your wrist. When you get your heart broken in any way, one of the hearts loses their colour and fades. Once all five have dimmed, it's said that you can never fall in love again. Enter Choi Beomgyu; a music major with only one heart left, barely hanging on a thin thread. He pledged to himself that he wouldn't find love again to save him from the curse. That changes the day Kang Taehyun joins the picture with five complete hearts, taunting Beomgyu. Out of spite, Beomgyu bets with his friend that he can break at least one of Taehyun's hearts. What's one heart less? What he didn't expect was to possibly fall in love in the process, leading to his demise.