Rio is considered very beautiful and cares deeply for Biko, shown in Volume Four of the series, when Rio blocked Biko from any harm from glass shards after Biko’s experiment exploded in class, and throughout the series Rio reminisces about the memories she shares with her student. She is regarded as a “charismatic artificier” and is quite the flirt, planting kisses on Biko and Muhyo, though she is unsuccessful with the later. She is more skilled than Biko at making artifacts, acting as her mentor before Biko went out on her own to make her name as an artificier. Though she comes off as friendly, she has a darker side filled with
guilt and anger due to the unfair death of her mother, whom she loves almost as much as Biko.
Rio originally worked as a teacher at the Magic Law School, while she lived with her sick mother. She usually wore revealing clothing, but her students complained (except Yoichi, who thought she looked fine), so she began wearing outfits that were more conservative. But her employer told her to wear less clothes, or he would make sure that no one would buy her artifacts. Soon, Biko became her apprentice, and after a while, went off on her own (Volume Four). Rio's mother was attacked one night by a spirit, so Rio ran for help. Her employer wouldn't help (claiming she was rebellious) and others thought she was "vulgar" for wearing revealing clothes. No one helped her save her mother, and she was killed, leaving a message for Rio made by using pieces of a broken comb: "Thank you, Rio". Vindictive at the Magic Law Association for not helping her and her mother, Rio turns into a traiter and joins Enchu and the Forbidden Magic Law association of Ark. She has a contract with the Flame Lizards, which gives her the ability to use her artifacts, particularly a wand, and use magic. Enchu and Teeki used her to break the seals on the Forbidden Law Book. We later find out the Teeki was the spirit that murdered Rio’s mother. Even though she was considered a traitor, she never stopped caring about Biko and near the end of the series is reunited with her and the gang, taking a slight sentence for her involvement with Ark.