Yuko Natsuki
About
Yuko begins having visions after coming in contact with Aiko, which turn out to be suppressed memories. After witnessing Aiko's past abuse at the hands of Kanetsugu and Hikiko, Yuko promises to protect Aiko's spirit, letting her live inside her body. Yuko also regains memories of herself having been abused by Kanetsugu in order to be prepared as a vessel for Aiko's spirit. Yuko and Aiko then work together to get revenge on Kanetsugu.
Later, it is stated that Yuko's mummified corpse was found in a psychiatric clinic, despite several claiming that they had met and spoken with her since her supposed death. It is implied that Yuko and Aiko are still wandering the earth as a merged entity, with some being able to see them.