A girl whose sleaziness can put even Class E’s perverted genie Taiga Okajima to shame, she also shows the keen intellect of someone known as a former child prodigy. At the same time, she also greatly enjoys teasing others, displaying a genius-level gift for it. She has a nose for finding people to mess with. Rio is also a friendly, energetic girl and somewhat of a trickster. Her favorite victim, along with Karma Akabane, is Nagisa Shiota. She's playful, has a dirty mind, and has been noted to be rather intelligent. She claims she was originally a serious person, something that would prove to be true when she disagreed with Nagisa's proposition to save Korosensei and continue to kill him. Despite her eccentric nature, she can see the bigger picture and hides how she feels, but she cares about Class E more than anyone. She also felt responsible for the bond between the class and Koro-sensei. On one hand, she can play the role of Class 3-E's resident mischief chick. On the other hand, when the situation calls for it she can be quite straightforward. Even Ryoma Terasaka started to wonder which between the two of them is the more outrageous kid in class.