Dunk and Joong have been together for years, a seemingly happy couple. But lately, Joong has been distant, always busy, or not fully present when they're together. Dunk finally discovers the reason: Joong is still in love with his first love, Est. This revelation triggers Hanahaki Disease, a rare illness where you cough up blood and flower petals because of unrequited love. Dunk has to make a painful choice: undergo surgery to get rid of the disease, but forget Joong completely, or let the illness consume him.