Mistrust is a droid sent by Emerald to fill a vulerable spot with dark energy. She can create several clones of herself that will vanish if attacked. She can also use her antennas to make people hallucinate and think their friends turned on them. She appeared in Sailor Moon R Episode 33, Smart Payoff.
Emerald sent Mistrust to the vulnerable spot located in Amy's genius school, Albert Einstein School for the Gifted. Everyone there fell under her spell and accused Amy of cheating. Amy discovered Mistrust and transformed into Sailor Mercury to fight her. Mistrust used her clones to attack Sailor Mercury, and when the other Sailor Scouts appeared, Mistrust made Sailor Mercury hallucinate that they turned on her. However, her powers did not have a big effect on Sailor Moon, as she receives negative comments all the time. Her clones even threw Tuxedo Mask out the window when he arrived. However, what Mistrust didn't realize was that the power of friendship is stronger than her illusions, and Sailor Mercury destroyed her antennas with Shine Aqua Illusion. Sailor Moon destroyed Mistrust with her scepter. (Once again, saying "Activation" instead of "Elimination")