"Big brother! I like you the most. Although I have only known each other for a day, I still like you so much! You are so gentle!" "Really? Do you want to be my bride?" "Yeah!" "But you have to let me take a bite! We will forget each other in the future! If we forget each other and don't fall in love in the future, then you will Die when you're an adult!" "It doesn't matter! I will definitely make my eldest brother fall in love with me! He's so handsome, so he has to let me do it, right?" ..." "Well, tick..." Just like that, a seventeen-year-old boy who was about to die made an agreement with a helpless four-year-old girl under the red moon, and then the two separated... Twelve years later, the two people who had forgotten each other had undergone tremendous changes... The boy became a blood prince, became ruthless, and only had power and bloodlust in his eyes; the little girl Now a slim girl, she has the ability to feel the breath of vampires due to the curse. She is regarded as a "hallucination" by the world and is locked up in a mental hospital... The girl who has forgotten her four-year-old childhood escapes from the mental hospital in order to understand the strange curse on her body (an agreement she made with a boy twelve years ago) and enrolls in a school for abnormal people, Holy Night Academy...