Manga
Viluy was a rank 202 in the Deathbusters. She was stsated to be Sailor Mercury’s counterpart in powers and intelligence. During her appearance, she attempted to attack Sailor Mercury using the identity of Bidou Yui. She was stopped (and killed) by Sailor Uranus.
Anime
Yui Bidou was Sailor Mercury’s foil in and out of battle. Her acadmics were top of the line and gave Ami Mizuno (Sailor Mercury’s civilian identity) a run for her money. She constantly called Ami weak for being too emotional and sensitive. She believed herself to be extremely logical. She believed logic and science always won out against emotions.
This was to her disadvantage, however, as her nanobots turned on her and destroyed her.