Lee Sil-bi is an angel who descends to earth and becomes human to protect Shin Woo-hyun. The guy lives with his grandmother, he is emotionally cold and very popular at school because of his handsome looks and vocal abilities. When his best friend Hwan Seon-yeol learns that Woo-hyun's biological mother will become his stepmother, the two friends become rivals. Their rivalry intensifies even more when both fall in love with classmate Sil-bi.