Choi Yoo Jung, an ordinary college student, finds herself in debt to a cafe called “Delicious Blood” one day due to a certain incident. A huge debt of 100 million won. Daniel, the owner of the cafe, tells Yoo Jung to pay off her debts by working part-time at his cafe, to which she eventually did so. However, the handsome boss Daniel doesn't think of letting her off the hook so easily. He leans towards Choi Yoo Jung and says something she didn't understand. What exactly is Daniel's identity? And what will happen to Choi Yoo Jung's future?