*She made her debut in Shantae: Risky's Revenge as the game's final boss, appearing as a colour swap of Shantae. Nega-Shantae also makes a brief appearance in Shantae: Half-Genie Hero when Shantae's magic is converted to dark magic. This later became the basis for the Friends to the End DLC, where she once again served as the final boss.

Nega-Shantae serves as Shantae's opposite, featuring a complete color palette swap from the original character. Unlike Shantae's blue eyes, purple hair, red clothing, and darker skin tone, Nega-Shantae has green eyes, red hair, purple clothing, and light grey skin. In her animal forms, Nega-Shantae's design remains consistent with this opposite theme. Her monkey form has red eyes and predominantly light purple fur, with grey fur on her face, tail, hands, and feet. In her elephant form, she sports much lighter grey skin and wears a slightly pinkish saddle and jewelry, replacing Shantae's purple ones. Her mermaid form features red hair and light grey scales instead of Shantae's green scales and purple hair. In Half-Genie Hero, Nega-Shantae adopts a more sinister and demonic appearance, displaying a monstrous expression and summoning flames in her hands.

In contrast to Shantae's goodness, Nega-Shantae embodies pure evil and appears to lack any of Shantae's positive character traits. In Risky's Revenge, Nega-Shantae seems to have no personality beyond her malicious nature, likely because she is merely a product of Shantae's corrupted magic. However, when Shantae transforms into Nega-Shantae due to her exposure to dark magic, Nega-Shantae fully represents Shantae's opposite. She reveals her personality during a brief speech directed at Shantae's friends, during which she expresses her deep disdain for them and all beings she perceives as weak and pathetic—potentially every creature in Sequin Land. Nega-Shantae exhibits sadistic tendencies as she commands them to beg for their lives. Furthermore, she takes pleasure in watching a defeated and desperate Shantae plead for mercy on behalf of her friends. In response, Nega-Shantae reminds Shantae that she is completely powerless to control her actions and has failed to protect her friends and family.*