Tasha makes her first appearance ten seconds into the game's opening cinematic, as she enters the spirit village with her two goons, Doi and Gong, to steal the sacred "pearl of will" (意志の珠). To her dismay, however, it had already been stolen by a mysterious figure minutes before.
Throughout the adventure, Tasha's trio attempts to steal more "pearls of will", only to be thwarted by the party each time. However, she gradually develops an interest in the main hero, Array, and eventually redeems herself when she helps save him and his party from a murder attempt by the game's primary antagonist, Radius.
Despite her appearance, she is actually fairly polite throughout and shows little signs of genuine malevolence. By contrast, the game's other villainess Sharon is much more sadistic.