Opera is a character in the anime Metallic Rouge who presents herself as a performer in a mysterious traveling carnival troupe that journeys across the solar system. In public, she adopts the appearance of a gothic lolita circus entertainer, a persona that allows her to move freely and avoid scrutiny while the troupe travels from city to city.

Beneath this theatrical surface, Opera serves under a figure known as the Puppeteer and secretly operates as a core member of the Usurpers, the alien faction that plays a significant part in the story's larger conflict. Her association with the carnival is therefore a cover for her true allegiance, and her loyalty lies with the Puppeteer and the Usurpers' interests rather than with the human institutions that govern the world she moves through.

Because of her exceptionally high physical abilities, Opera is generally presumed to be a Nean, one of the artificial beings that coexist with humans in the series' setting. However, her true identity is not immediately revealed, and the ambiguity around what she actually is forms part of her intrigue. Her abilities make her a dangerous presence despite her unassuming performer persona, and she is capable of operating in environments where ordinary people would be vulnerable.

In the story, Opera occupies an antagonistic role, working behind the scenes as part of the carnival's hidden connections to the Usurpers. Her key relationships are defined by her position within that hierarchy: she serves the Puppeteer directly, and her true bond is to the Usurper cause rather than to the troupe she appears to belong to. Her development is tied to the gradual uncovering of her real nature, as her initial presentation as a simple carnival member gives way to the revelation of her deeper role in the series' unfolding events. Her notable abilities include her physical prowess, her skill at disguise and infiltration through her performer cover, and her capacity to operate as a capable and committed operative for the forces she truly serves.