One day when visiting the SEKAI, Mizuki notices a strange doll-looking girl sitting against one of the cold prisms. She walks over to it, getting a closer look.

The girl looks human, her skin is soft and hair shiny. The only thing strange is the fact that her eyes look empty, almost dead. Mizuki puts one hand under the girl's chin, tilting her head up.

"Hmm... What are you..?"