Viluy (ビリユイ Biriyui) is a villain in the manga series Sailor Moon. She is the white-haired member of the Witches 5 with a rank of Level 202 and able to use nano-machines to completely obliterate her enemy in her "Mosaic Buster" attack, named for the mineral viluite. She acts under alias of Yui Bidoh (美堂ゆい Bidō Yui), Mugen Academy's top student and prefect of the Computer Club, using her nano machines to turn computers into Hoste-sucking machines for the Mugen Prep School held in Mugen Academy. Viluy attempts to take Mercury's soul, but ends up being killed by Sailor Uranus. When Kaolinite revives the Witches 5 for her curse against the Sailor Guardians, Viluy targets Mercury's insecurities and later attacks Sailor Moon before destroyed by the Outer Guardians.
In the anime, Viluy is handed the task of gathering pure hearts after Tellu's death. She collects the pure hearts from the students using a supercomputer, controlled by her wristband. She overpowers Sailors Mercury, Uranus and Neptune using nano machines controlled by her wristband. Sailor Moon damages Viluy's wristband and the Witch ends up being consumed when her Mosaic Buster rebounded on her.
Viluy also appears in the stage musicals. She is voiced by Yoshino Takamori in the original anime and by Rina Hon'izumi in Crystal. In the Cloverway Inc. English adaptation, her names were changed to "Byruit" and "Julie Bidoh" and is voiced by Daniela Olivieri. In the Viz Media English adaptation, she is voiced by Julie Ann Taylor (as name of 'Cricket Brown'). In the musicals, she is played by Nao Futatsugi, Yuka Kuwahara and Yui Hasegawa.