Cardcaptor Sakura

Sakura, Toya, and Cinderella (1x14)

:

Sakura is invited to her brother's high school culture festival. She meets Tomoyo and Syaoran there and catches a play by Yukito and Toya's class. During the play, a mist forms outside the auditorium and enters through the vents where it destroys the stage and puts Toya and a girl named Yoko in danger.