She is also known as Fake Ishtar or False Ishtar.
Succubus first appears in The Tower of Druaga. Here she serves as Druaga's right-hand woman. She is given charge of guarding the Blue Crystal Rod on the 57th floor of the Tower of Druaga. She disguises herself as Ishtar, the goddess of love. This is to deceive Gilgamesh (Gil), who is trying to rescue his beloved Ki. However, Gil uncovers Succubus' trick and has a debate with her. After Gil wins the debate, Succubus relinquishes the Blue Crystal Rod.
Succubus later appears in the Japan-only sequel The Blue Crystal Rod, which is the final game in the original series. She is a minor character here, who may or may not be encountered by the player depending on their actions. Here she has left the Tower of Druaga and returned to a cave dwelling.
Succubus also appears in the 2008 anime based on the games. This takes place 80 years after the original, and Succubus is shown as a resident of the Tower of Druaga once more.
She is released by Neeba, a young man ascending the tower. Once she was released, Succubus haunts Neeba and torments him. Succubus is invisible to others except when she chooses to make herself visible. She also interferes with the Tower of Druaga's system.
Succubus' physical appearance differs between the games and the anime.
While not apparent in the arcade version of The Tower of Druaga, in the PC engine remake and The Blue Crystal Rod Succubus is shown with wavy blonde hair, two horns, and bat wings on her back. In the PC Engine version she is revealed to be topless, possibly suggesting nudity.
In the anime however, Succubus has straight blue hair and lacks horns. She is also fully clad, in white and blue clothing.