Shin Woo Hyun (Nam Woo Hyun) has lived with his grandmother since he was a child. He is kind and upright and has a dream of music. He is very popular among girls. However, the dark memories of his childhood have built a thick barrier in his heart, which does not allow any invasion. A new boarder named Lee Seul-bi (Kim Sae-ron) came to Shin Woo Hyun's home. This mysterious girl with unknown background soon attracted Shin Woo Hyun's attention. It turns out that Lee Seul-bi is an angel from the divine world. Because of an accident, she was demoted to the human world. In Heaven High School, she hid her true identity while looking for a way to become an angel again. As time goes by, the distance between Shin Woo Hyun and Lee Seul-bi gradually narrows, and a sincere relationship develops between the two. However, how can Lee Seul-bi, an angel, fall in love with humans? Between heaven and the human world, what choice will Lee Seul-bi make?