Ryoko Otonashi's personality consists of a forgetful girl due to her illness, with a carefree emotion and not caring about many things. Because of her forgetfulness, she carries a notebook with her labeled as "Ryoko Otonahi's Memory Book", which she writes in constantly in order to try and remember events. The only thing she can remember clearly is her crush Yasuke Matsuda, which she wants to be with constantly. Her main phrase is "This has nothing to do with me!", and will always say that, even if the event does have something to do with her.
Ryoko's appearance is very basic. She has messy, long dark red hair, along with dark red eyes. Her outfit consists of the Hope's Peak Academy uniform, which consists of a brown cardigan and skirt. Her cardigan is unbuttoned and has the Hope's Peak logo, and under it is a white blouse with a red bow. She wears white knee-high tights and brown shoes.