Ling, a 17-year-old high school girl, lost her mother at a young age. She hated her mother for leaving her to save a strange child. She used to love singing, but now she is depressed and no longer speaks. However, by chance, she enters the virtual world U with 5 billion users. Here, she begins to sing naturally and unrestrainedly, and quickly becomes popular, becoming the most popular online singer in the world. Ling, who has freckles on her face, lacks confidence, and can't find her place in the real world, successfully hides behind the glamorous masked personality Belle in the virtual world. Just as she is standing on the stage of the largest concert in the U world with great ambition, the real challenge comes. A mysterious dragon suddenly appears and destroys the concert. Who is the dragon and why is his body covered with scars? On the way to explore the truth, Ling awakens her own courage and strength, overcomes the challenge with love and singing, and finally realizes her self-salvation while reaching an understanding with her mother.