Yuu Abiko

Also known as "Biko", is she is a Magic Tool Artificer, who is able to make magical tools, but cannot use them herself. She is deeply devoted to her teacher, Rio, and is shocked by the revelation that she is a traitor. When she was younger, she disliked Rio until Rio saved her from an experiment gone wrong. Roji first believed she was a boy when she first appeared. She has three apprentices of her own. She hopes that Rio can be saved, and wishes to go raspberry picking with her.

(Source: Wikipedia)