Prince Kyanite is a human living in a world where vampires exist. One day, he is slain by the Tenth Vampire Prince. Supposedly, that's how his story should've ended in the animation titled: The Tragedy of a Human Prince.
Coincidentally, his death scene crossed the same time, day, and place when the gold-medalist Olympic swimmer, Lazuli Savelli, drowns and dies. As if by fate, she discovers herself reborn in the male body of Prince Kyanite, thus, downright altering the tragic ending of the animation.
Puzzled and upset about these new and strange events in her life, Lazuli, as the new Prince Kyanite, explores this unfamiliar world where she, eventually, gets entangled in situations involving the very slayer of her character—Prince Chalcedony!
Now, the only way to escape another tragedy she thought of was to get into the good graces of the beautiful and powerful Vampire Prince. However, the big question is: how will Lazuli do that when she knows nothing about the original Human Prince?