Arianna Hyama Aleardi is a young woman of seventeen to eighteen years old with black hair and blue eyes. Her heritage is a mix of three-quarters Italian and one-quarter Japanese, a trait she inherits from her Japanese grandfather. She is known to go by the nickname Anna.

Arianna serves as the personal maid to the knight Erica Blandelli, and through this position, she is also an apprentice member of the magic society known as the Copper-Black Cross. Despite her affiliation with this magical organization, Arianna possesses little to no talent for magic, which at one point nearly led to her being expelled from the society.

Her personality is notably carefree. This trait is demonstrated on several occasions, such as when she laughed at being addressed formally and when she nonchalantly left the Campione Godou Kusanagi at the Colosseum without much concern.

In her role as a maid, Arianna is highly proficient in nearly all forms of housekeeping and serving duties. However, she has a notable weakness in the kitchen, as her soups and stews are consistently terrible. A more paradoxical skill is her driving ability. She is characterized as a terrible and reckless driver who operates vehicles at high speeds, yet she has miraculously never been involved in an accident. Her driving skills have proven useful, such as when she transported Godou Kusanagi and Erica Blandelli to confront a heretic god.

Her primary relationship is with her master, Erica Blandelli, to whom she is utterly devoted in her capacity as a maid. She appears in several volumes of the light novel series, including volumes one through four, eight, and twelve, and is mentioned in others. Her role in the story is largely supportive, providing transportation and domestic assistance to the main characters.