Lee Hyeon is a perennial bachelor (motae solo) who juggles multiple part-time jobs to pay off debt and hospital bills, never daring to dream of dating. During one of his coffee delivery shifts, Hyeon bumps into the famous model, Sian (시안), and is suddenly robbed of his first kiss! "Let's sign a contract, you and me." Not content with selfishly stealing Hyeon's precious first kiss, Sian abruptly proposes a contractual relationship. But Sian's true identity is shocking... an Incubus?! Can the innocent, perpetually single Hyeon safely graduate from his "Cherry Boy" status under the guidance of a mischievous celebrity demon?