Zeniba is the identical twin sister of Yubaba, the witch who is the main antagonist of Studio Ghibli’s Spirited Away (2001). Zeniba is also a witch, but she lives in a cabin in Swamp Bottom, far away from her sister’s bathhouse in the city. The two express much distrust and distaste for one another, using words like “hate” and “polar opposites,” and Chihiro finds herself accidentally caught in their sibling rivalry.
Zeniba is so much like her twin that there is virtually no difference in their appearance–they are physically identical, and they also wear identical clothing, make-up, and jewelry. Because they are voiced by the same actress, they also sound exactly the same. On occasion, though, Zeniba wears a pair of spectacles–an accessory that her sister seems either not to need or not to acknowledge needing. That small pair of glasses is actually a fairly large indicator of the real differences between Zeniba and her sister–because they are neither identical (as suggested by their appearances) nor are they opposites (as the two of them suggest). Zeniba and Yubaba are in many ways the inverse of one another, mirror images who, in that uncanny sort of way, are both identical and opposite.
When Chihiro first encounters Zeniba, the two face-off over Haku. Chihiro sees a wounded Haku being attacked by paper spirits, and she goes into Yubaba’s office where he has fallen. Haku is almost pushed down the garbage chute by the Kashira, but Chihiro stops them, hoping to save his life. Boh crashes into the room and begins to cry, and Zeniba reveals herself as a paper spirit that attached itself to Chihiro’s back to find Haku. Zeniba changes Boh into a chubby little mouse, Yu-bird into a tiny crow, and makes the Kashira into an imitation of Boh. She leaves Chihiro intact in exchange for showing her where Haku is and threatens to harm her if she tells what has happened. But Chihiro will not relinquish Haku, not even after Zeniba explains why she’s been hunting Haku–he stole a golden seal from Zeniba and is dying because of a curse put on the seal. When she turns her back to deal with the Kashira again, Haku rips the paper that had been projecting her form, and she disappears. Chihiro and Kamaji manage to get Chihiro to cough up the seal he’d swallowed, and with it comes a slug that Chihiro squashes.
But now Chihiro must figure out how to save Haku, who she has come to care for deeply—and she decides to do so by repairing the rift between him and Zeniba, who turns out not to be quite as fierce as expected. Chihiro travels to Swamp Bottom with Boh, Yu-Bird, and No Face (who must leave the bathhouse after the trouble he caused), planning to return the seal and apologize to Zeniba on Haku’s behalf. Zeniba greets the quartet kindly, opening her door widely and inviting them in for tea. Chihiro hands Zeniba the seal and apologizes, telling her the story of retrieving it. She laughs and says that the slug was actually Yubaba’s way of controlling Haku and that Chihiro has saved Haku twice over–breaking the spell binding him to Yubaba and loving Haku enough to break Zeniba’s curse. She and Chihiro form a bond, and Chihiro calls her “Granny.” She gives Chihiro advice on how to help Haku remember his true name, and when Chihiro prepares to leave, Zeniba offers No-Face a place as her apprentice.
Though we don’t see Zeniba after Chihiro leaves her cottage, it is clear that even Chihiro has begun to understand Zeniba’s true resemblance to Yubaba. This is made even more clear when Chihiro calls Yubaba “Granny” before she faces her final test.