Delta hails from the Tribe of Shadow, possessing gray skin, long cyan or white hair, red eyes, pointed purple ears, and distinctive red tattoos. Functional brown bat wings grant her flight. Her typical attire consists of a purple bra, panties, and a necklace. Abilities include flight, extended longevity inherent to her tribe, and combat expertise with twin daggers. Her demonic features suggest succubus-like qualities.

Within the game, Delta emerges primarily in the latter half, often encountering sexually charged situations. One of five possible endings pairs her romantically with the protagonist Astral, an outcome introduced in the Windows 95 remake. Choosing other character endings leads to her marriage to Rigel.

The anime adaptation significantly expands her role. Her intense curiosity drives her to secretly follow the antagonists Tessio and Menza, leading to her capture, rape, and brainwashing. Under their control as a hypnotized agent, she attempts to assassinate Astral, furthering Tessio and Menza's scheme to prolong the war between the Tribes of Light and Shadow. She is eventually freed from their influence.

A later comedic Omake special, set post-main storyline in a non-canonical scenario, features her interacting with other female characters vying for Astral's attention, where she succeeds in gaining his focus over rivals Sharon, Nina, and Mew.