A character from the adult doujinshi series, Rougetsu Toshi.
Playtime with Erika.
Michinoku is an evil spirit who, years prior, had been confined inside the body of a toy puppet. Her spirit companion, Rei, was also trapped inside of a teddy bear. Both toys were owned by Erika, a child born between a ghost and a human, during the time that she lived at her grandmother's home. Taking advantage of the girl's loneliness, the animated toys befriended Erika and played with her in order to gain her trust. Then, one day, Michinoku and Rei persuaded Erika to destroy the protective charms that had been placed in her grandmother's residence, allowing the two evil spirits to take on human form. Michinoku and Rei then sexually assault Erika, and subsequently kill the girl's grandmother as she returns home.
Michinoku ravishes a student.
Years later, Michinoku and Rei become teachers at an academy in policewoman Suzuka Itami's area. There, the two spirits manage to implant special parasites inside half of the female students, which give half of them the ability to become futanaris. The half who did not make such a change were then paired up with the futanaris by Michinoku, using a randomized, lottery-style method of selection. After all the pairings had been made, Michinoku tells the futanaris to sexually assault their partners, causing one of them to freak out and attempt to escape the classroom. However, the phallic parasite within the girl's stomach immediately bursts out of her anus begins raping her vagina until she dies. Michinoku tsk-tsks at the girl's disobedience and uses her as an example to the rest of the class that she will not tolerate any sort of rebellion.
Michinoku's final showdown.
The eager futanari students begin raping each of their partners, while Michinoku, who sprouts her own enormous penis, assaults the partner of the disobedient girl. After the ritualistic orgy, the non-futanari females each give birth to a fully-grown female spirit, which kills them in the process. Michinoku then explains that she plans to discreetly slip these ghosts into companies and society with the intention of creating world chaos, and that eventually, all humans will become playthings for spirits such as herself to rape and enslave. Her victory speech is short lived, however, when a member of Suzuka's police force appears and then swiftly decapitates her.