Yayoi Yukino, operating under the codename La Andromeda Promethium, is the current Millennial Queen dispatched from the planet La Metal to oversee Earth. Arriving on Earth as an infant, she was adopted by an elderly couple. Her Earth life sees her residing in a high-class apartment while working as a mathematics teacher and serving as an assistant to astronomer Professor Amamori. This identity masks her true mission: preparing for La Metal's imminent approach and facilitating humanity's subjugation. Her design embodies Leiji Matsumoto's distinctive visual aesthetic, featuring a tall, slender frame, waist-length blonde hair, and expressive eyes. In her civilian role, she favors practical attire like long-sleeved shirts and jeans. Her Millennial Queen regalia consists of a black dress and a red crown bearing a heart-shaped jewel, visually underscoring her dual existence as both an Earth educator and an alien sovereign. The film's New Age elements reflect her cosmic connection. Initially loyal to La Metal, her perspective shifts as human connections deepen, particularly with her students and Professor Amamori's nephew, Hajime. When La Metal's trajectory threatens Earth's destruction on September 9, 1999, she rebels against her mother, Holy Queen Larela, rejecting the planet's agenda of human enslavement. This defiance escalates into conflict with La Metal's military forces, commanded by her fiancé Dr. Fara, who remains dedicated to the invasion. Her emotional bond with Earth compels her to reveal La Metal's plans to Professor Amamori and Hajime, forging an alliance to save humanity. Her abilities encompass enhanced longevity, rapid healing, and crown-amplified psychic powers. She demonstrates telekinesis potent enough to halt natural disasters like tsunamis and experiences painful clairvoyant visions forewarning catastrophes. These powers derive from the accumulated knowledge and memories of prior Millennial Queens, accessed through her crown. Key events involve her orchestrating humanity's shelter within the Noah ark-ship concealed beneath the Kanto Plain and defending Earth using repurposed weaponry from a museum. She duels a successor dispatched by Larela on Venus, emerging victorious yet conflicted by the violence. The climax requires her to pilot the spacecraft Carmilla into a black hole destabilizing La Metal's orbit, sacrificing herself to redirect the planet and save both worlds. This act, aided by a reconciled Larela, resolves the immediate threat but severs her Earth ties. Her departure concludes with a farewell to Hajime, her foster parents, and Professor Amamori, highlighting her transformation from covert operative to Earth's protector. The film implies her eventual evolution into Queen Promethium of the Machine Empire, linking her to broader narrative elements within Matsumoto's universe.