Sailor Aluminum Siren is the second of the Sailor Animamates to appear. Her human pseudonym in the anime is Reiko Aya, which may be a pun on "puppet," "mermaid," "makeup" and "child spirit."

In the manga, Aluminum Siren first appears in Act 44 on the roof of Juuban High School and attacks Usagi and Seiya with Galactica Tsunami. She succeeds in stealing the starseeds of Sailor Mercury and Sailor Jupiter, killing them; but is eventually killed herself by Sailor Star Maker and Sailor Star Fighter. Aluminum Siren won Galaxia's favor by stealing the starseed of her native planet's Senshi, Sailor Mermaid. According to the Materials Collection her hobby is ballads.

In the anime, Aluminum Siren makes her first appearance in Episode 182. She's very polite, ditzy and oblivious when off-duty, and is always eating or feeling hungry; once engaged in battle, however, she drops her flaws and becomes completely ruthless. Masquerading as Aya Reiko, she works together with Karasuma Akane aka Sailor Lead Crow, who reveals that they once competed for the position of Number One Animamate. She eventually discovers Sailor Moon's identity and nearly succeeds in killing her, but is stopped by the Guardian Senshi and the Sailor Starlights. Despite learning their identities, Aluminum Siren is killed by Galaxia in Episode 188 for her failure to defeat Sailor Moon. She is the only Animamate who uses her manga attack (Galactica Tsunami) in the anime, although it consists only of throwing nearby water bottles, juice boxes, soda cans, and the like at the Senshi.