Viluy (known as Byruit in the dub) is the fourth member of the Witches 5, named after the mineral viluite. In the anime, she was assigned to collect pure hearts following Tellu's defeat. To accomplish this, she hacked all the computers at Infinity Academy to extract the pure heart crystals of students during a national practice exam. Additionally, she wielded the "Mosaic Buster" attack ("Mosaic Energy Blaster" in the English dub), which unleashed a swarm of nanobots from her wristband. Initially, she had considerable success and nearly overcame Sailor Uranus, Sailor Neptune, and Sailor Mercury, against whom she harbored a personal grudge. However, her wristband malfunctioned due to damage inflicted by Sailor Moon, causing the nanomachines to dissolve their own master, effectively killing her and leaving only her bracelet behind.
In the manga, Viluy appeared as the third witch, before Tellu. She held a rank of Level 202 and led the Science Division at Infinity Academy under the alias Yui Bidoh. Her storyline in the manga is largely similar to that in the anime, with the difference that she meets her end when Sailor Uranus slices her in half with the Space Sword.
