|Lives:||Witches 5 laboratory (presumably in Tokyo)|
|Occupation:||Member of the Witches 5|
|Associates:||Professor Tomoe, Witches 5|
|First Anime Appearance:||Believe in Love! Ami, a Kind Hearted Senshi|
|First Manga Appearance:||Act 27 Mugen 1 Yokan|
|First PGSM Appearance:||N/A|
|English Name:||Byruit/Julie Bidou (dub), Viluy/Yui Bido (manga, Viz dub)|
|Actors:||Yoshino Takamori (anime), Rina Honnizumi (Crystal), Kim Bubbs (dub), Cricket Brown (Viz dub)|
Viluy was the fourth member of the Witches 5 to appear in Sailor Moon S, and the third member in the manga. She had power over ice and also used technology and nano robots to attack her victims.
Viluy made her appearance in episode 122 of the anime. In her civilian guise as Yui Bidou, she attended Mugen Academy, and was an academic rival to Ami Mizuno.
Viluy appeared as a tall young woman with long pale blue hair, and was extremely intelligent and logical. At one point she accused Ami of being too sensitive and emotional, as she only believed in logic and science, and thought that those who believed in emotion were weak. She was killed when Sailor Moon's Rainbow Moon Heartache attack caused her bracelet to malfunction and her nano robots turned on her.
In the manga, Viluy was stated to be Sailor Mercury's counterpart, and was capable of transforming into a Daimon. As Yui Bidou, she was the leader of the science class and was ranked at Level 202. She met her demise at the hands of Sailor Uranus.
- Mosaic Buster
| Yuka Kuwahara as|
Viluy appeared in the musical Mugen Gakuen - Mistress Labyrinth and its revision, and was played by Nao Futatsugi and Yuka Kuwahara. She was apparently known as a scientific researcher in the musicals, as she was instantly recognized by Ami as the famous Yui Bidou.
- Mosaic Buster
Viluy appeared in chapter five of the video game Sailor Moon: Another Story, as a boss in Crystal Tokyo.
- Viluy is named for viluite, a silicate mineral.
- In the French dub she was never given a name, and had two different voice actresses: one for her Viluy form (Agnès Gribe) and a different voice for her Yui Bidou form (Amélie Morin). She was also nameless in the Hungarian dub, which was based on the French dub, though in that dub she only had one voice actress. In the Brazilian dub she also had two different voice actresses.