Erica's personal maid, chosen by her master due to being able to speak Japanese and having Japanese ancestry. According to Erica, Arianna is smart, responsible, hardworking, that she is a perfect maid even she has four small "interesting" weaknesses. Her four weaknesses are dangerous driving skill, bad at cooking, no ability of fencing or using magic, and making a big mistake every three days. Arianna hasn't notice these weaknesses at all.
Despite she has dangerous driving skills, she has never cause accident or injured anyone.