On the night of a blue moon lunar eclipse that happens once in ten years, the portal between the vampire world, where drinking human blood is forbidden, and the human world opens. Lucifer, a vampire prince who desperately craves human blood, descends into the human world. Min U, a university student in his early twenties, moves to the city from the countryside. He works tirelessly, day and night, to save up for tuition while also studying hard.
However, Min U contracts a rare disease that puts his life at risk whenever he bleeds. One day, Min U becomes a victim of a hit-and-run accident, bleeding and finding himself in a life-threatening situation. Lucifer, drawn by the scent of blood, attacks Min U. However, something strange happens: Lucifer collapses, and Min U miraculously survives, unharmed.
