The eleventh episode of Anastasia's Magical Wish.
Homura and Mami recover from grieving over Madoka, Sayaka, Christine and Courtney's deaths, but Stacey doesn't. When she finally does, though, she confesses to Mami that she is the youngest Puelian on Earth. Later, Stacey and Homura stay the night at Mami's home, and Homura and Mami witness Stacey suddenly die and become a witch!
Stacey (turns into witch)
Soon-to-be Puella Magi