Empress Necros rules the Inma Empire, a perverted force seeking to dominate Earth and transform it into a sexual empire. She is the daughter of the Greek god Apollo, reinterpreted here as the deity of lust, and seeks to resurrect him to achieve her empire's goals.

Operating covertly on Earth, she assumes the human identity of Dean Narumi, dean of Golden Star Academy. From this position, she directs the Inma Lords—high-ranking members disguised as faculty: Marquis Saturn (English teacher), Count Uranus (math teacher), Viscount Neptune (biology teacher), and Baron Pluto (physical education teacher).

The Empress and her Lords specifically target five schoolgirls, the Venus Warriors, who bear hidden Venus marks granting supernatural abilities. They employ various methods to locate these marks and neutralize the Venus 5, viewing them as the primary obstacle. Empress Necros is partly futanari.

Her narrative unfolds across the original video animations "The Inma Ball" and "Labyrinth of the Inma." In "The Inma Ball," she oversees initial efforts to identify and capture the Venus Warriors, successfully discovering Venus Purple (Ai Misora). "Labyrinth of the Inma" expands her story, featuring Emperor Nero, an abusive elf subordinate tasked with guarding Apollo's casket. She serves as the central antagonist in both installments, her leadership focused on achieving the Inma Empire's objectives through manipulation and direct confrontation with the Venus 5.