Mileina Vashti is the daughter of Ian and Linda Vashti, the chief engineer and a developer respectively for the paramilitary organization Celestial Being. Growing up surrounded by her parents' work, she absorbed a deep understanding of engineering, GN technology, electronics, robotics, physics, and programming. She joins the crew of the Ptolemy as a tactical operator in the Combat Information Centre and also serves as a mobile suit mechanic, inheriting her father's technical skill. Mileina is youthful, highly upbeat, energetic, and optimistic, often described as the mood-maker who brightens the atmosphere of the ship. She is a romantic and easily excited person who can become bored with repetitive tasks and may pout when things are down. Her cheerful personality provides a contrast to the more serious senior crew members and Gundam Meisters. In the film, Mileina continues to serve on the Ptolemy II, participating in humanity's first contact with the extraterrestrial life form known as the ELS and the final battle to protect Earth. Her key relationships include her father Ian, whom she works alongside, and a deep, unreciprocated affection for Tieria Erde. In the movie, she finally confesses her love for Tieria after he sacrifices his physical body to save Setsuna. Over the course of the story, Mileina matures from a girl with a childish air into a more womanly young woman, though her fundamental cheerful disposition remains unchanged. Her notable abilities include her technical expertise as a mechanic and her role as a capable tactical operator, supporting the Gundam Meisters from the command centre.