In-joo, who had lived a lonely, abandoned life, encounters Jin-do, a bright, warm-hearted man. Jin-do is the first person in her life who takes care of her and gives her love. For the first time in her life, In-joo dreams about being happy for once. But now, In-joo has one last request: she wants Jin-do to let her go, like a summer cold that people have no regrets after suffering.