Jumeau is a female youma under the control of Nephrite in episode 018 (Shingo no junjou! Kanashimi no France ningyou). Her mission is to gather the energy of doll maker Mika Kayama once she reaches her peak energy output. Nephrite puts his evil crest on a French doll made by Mika, causing her to become obsessed with making ten replicas of the doll and hastening her approach towards her peak energy output. At Mika's mother's next doll show, Mika reaches her productive peak. Jumeau immediately emerges from the doll and drains all of the girl's energy. Shingo Tsukino is on the scene, and he rushes forward towards his friend, only to be knocked against a wall by the youma. Because Shingo is unconscious, Usagi takes the opportunity to transform into Sailor Moon and challenge the youma. A doll with very sharp teeth flies towards Sailor Moon, but she manages to dodge it. She leaps through a nearby window, and Jumeau comes crashing through after her. Sailor Mercury and Sailor Mars soon appear, and Sailor Mercury uses her Sabão Spray attack to fill the air with bubbles and confuse the youma. Two dolls fly towards the three girls, but Sailor Mars uses her Akuryou Taisan attack to incapacitate them. Meanwhile, Jumeau finds Sailor Moon and begins to strangle her as Mercury's bubbles fade. Sailor Mars uses Fire Soul to attack the youma and destroy her arms, but she is able to regenerate them immediately and fire them at the senshi. She is able to the same with her legs. Sailor Mercury uses her visor to detect the youma's weak spot, which is located near her right foot. Sailor Moon tries to attack, but Jumeau's detached hands are sill strangling her, and she is unable to call out the name of her attack. Fortunately, Tuxedo Kamen arrives just in time. He throws a rose at Jumeau, breaking her concentration and causing her limbs (including the ones strangling Sailor Moon) to reattach themselves to her body. Once she is free, Sailor Moon uses her Moon Tiara Action attack to hit the youma's weak spot and destroy her. Mika's energy is immediately returned to her.
Jumeau has a doll-like, disjointed white body and blue hair. She wears no clothing except for a necklace bearing Nephrite's evil crest. Jumeau gets her name from a type of antique French dolls made by the doll maker Pierre Jumeau. These dolls were made during the 1800s, and they look almost exactly like the dolls that Mika Kayama makes. The dolls are highly prized among collectors.
(Source: The Oracle :: BSSM Encyclopaedia)