You in Me.

Qiao Ran, an alien, arrives on Earth with a mission, to integrate himself into the life of Xia Mingqi, an Earth girl who has lost her passion for dancing. As Qiao Ran protects and encourages Xia Mingqi to rekindle her dream, she falls for his gentle nature. However, she begins to notice a strange phenomenon—no one else can remember Qiao Ran, and she herself seems to have forgotten him countless times...