Queen Seirena of the Alcantia Kingdom had dedicated herself to her country, supported by the words of her parents who died young. However, one day, everything was suddenly taken from her by an imposter identical to herself. Betrayed by her fiancé and abandoned in a prison cell where no one came to help, Seirena resigned herself to death. However, the one who appeared before her was King Plum of the neighboring kingdom. He revealed his true identity as a vampire who had lived for many years and posed a question to Seirena: 『Will you become a vampire and come with me, or will you wait for death?』 In order to reclaim everything, Seirena enters into a blood contract with him.