Ria, born Liavelt Von Neuestein on March 13, 2283, in New Lumberk, Germany, stands 163 cm tall and weighs 48 kg, with measurements of 80-58-85 and blood type A. She enjoys sewing and savoring delicious tea, and she is an expert marksman. Initially appearing as Yuna's rival in the first PC Engine game, Ria's path shifted dramatically after her defeat; she transformed from an adversary into one of Yuna's closest friends and allies, a significant evolution in her character across the series.

Simultaneously, Ria maintained a hidden life as the superheroine Polylina, star of the television show "Ojousama Kamen Polylina" (お嬢様仮面ポリリーナ). She kept this secret identity concealed from everyone, including Yuna. Unaware that her friend was Polylina, Yuna remained an ardent fan, declaring herself the "#1 fan" of the Polylina Fanclub and often expressing deep affection for the character. Yuna's enthusiastic fandom provided recurring humor within the narrative, frequently drawing subtle or amused reactions from Ria. Her activities as Polylina formed a distinct part of her life, separate from her direct interactions with Yuna's group, yet actively shaping the dynamic between them.