Though Mi-Soo underwent treatment for a brain tumor three years ago, the illness has returned, leaving her with a terminal prognosis. After her parents divorced, her mother remarried and her father died in a car accident. Raised by an aunt with whom she has a strained relationship, Mi-Soo has no close friends and no one she can rely on to arrange her funeral. Determined to find someone who will take on that responsibility, she crosses paths with Dong-Soo, who soon becomes unsettlingly devoted to her, following her everywhere like a shadow. Ten years ago, Dong-Soo loved Mi-Soo deeply. Now, as fate brings them together again, their reunion awakens old feelings and forces them to confront the love and loss they never truly left behind.