She was sent by Zoycite to spy on Neflite. After Molly protected Neflite from Sailor Moon's Moon Tiara Magic, Yasha appeared and attacked Molly. Neflite did the first good thing he had ever done in the anime and protected Molly from her, splitting Yasha's face in two. Yasha revealed her true form and attacked Neflite with her horns, which resemble drills, but Sailor Moon destroyed her with Moon Tiara Magic. Her final words were "You have destroyed me!"
Her name comes from the Japanese name Yasha (夜叉) which is a demon creature from folklore.