Li Xun happens to be the student that Zhu Yun's mom had expelled in high school for changing his friend's grades. Her mother is wary of him and tries to convince Zhu Yun to stop going to practice class to limit her interaction with him. Li Xun agrees because he thinks they are too different from each other, so he tries to exclude her from the Blue Crown project. Zhu Yun disagrees with her mother and tries her best to still help with the project. (Source: frankly at kisskh)