Sena Yamada is a second-year in high school. For various reasons, she lives alone. She manages to get by by holding down a part-time job. One day, when she was about to be cheated out of her money, she was rescued by a demon king! He told her that she is a reincarnation of a saint and even asked her to move in with him...?　 The exciting life together of a hardworking JK and a pushy demon king is about to begin!