This drama tells the story of a high school girl in Class 3C, next to Class 3D of Fenglai High School, the stage of the TV drama "The Best Teacher". The protagonist Ban Guang suffers from a genetic disease and is told that she has one year left to live. She secretly writes down in her notebook what she wants to accomplish in the limited time. She is called a "positive energy monster" by people around her, and in order to make the remaining time the best day, she chases youth brightly, strongly, and vigorously.