Giwaku was a Droid belonging to Esmeraude which appeared in episode 80. She had the ability to make her target see illusions of those they cared for turning on them and verbally abusing them. She tried to use this power to turn Sailor Mercury against the other Sailor Senshi, but instead Sailor Mercury used her attack on the Droid. This attack froze the antennae that Giwaku used to create the illusions, giving Sailor Moon the chance to destroy her.

(Source: Project WikiMoon)