Eiko is rather pleasant and polite in personality, with a formal manner of speech. She has medium-length light brown, wavy hair and her face is never fully shown, except from the side and at a distance, for reasons unknown. Since her only appearance is in episode 19 and she is absent from the original manga, it is likely that she was invented by that particular episode's script writer, Hajime Satsuki, unlike most of the other characters who are created by Kiyohiko Azuma.