Derella was a Youma summoned by Jadeite to drain energy from unsuspecting competitors as part of the Dark Kingdom's continuing energy-gathering efforts. She appeared in anime episode 7. In her Youma form, she had the appearance of a humanoid female made of glass, with no hair on top of her head but a yellow ponytail prodruding from the back.
Derella attacked the idol Mikan Shiratori and sprayed her with a blue webbing-like material, trapping her, then assumed her identity. As Mikan, she assisted Jadeite by creating a talent competition called the Cinderella Caravan, the winner of which was to get a contract like Mikan's. While announcing the competition, they used a device at the top of the stage to send out a wave over the crowd, hypnotizing everyone in the surrounding area into wanting to take part, and those affected included Usagi's friends Naru and Umino.
As the competitors later performed on stage, Derella sat in the audience and absorbed their energy through a lapel mike she wore on her shirt. After Usagi and Luna became suspicious after seeing all of Derella's victims performing to an empty audience, Derella then revealed herself as a Youma in disguise with a combination of her true form and her Mikan disguise. Luna persuaded Usagi to transform into Sailor Moon, and she then confronted Derella, who transformed into her true form.
Derella attacked Sailor Moon by blasting more glass webbing at her from her mouth, and eventually encased her in glass. Tuxedo Mask arrived in time to help, and threw a rose that shattered it. Derella flew up to follow him as he left, but Sailor Moon destroyed both the Youma and the energy-absorbing pin with her Moon Tiara Action attack.
