Rio has ash brown hair that appears to look gray, she also has blue eyes that look gray in the anime. She wears her hair in pig-tails with ribbons, or she is seen with her hair down. She ether wears her red, white, and black uniform, or she wears her pajamas, and also sometimes other clothes.
Rio can be child-like. She can be nice, and sweet, though she can get mad easily and this is what people should look after for. She loves to eat melons and always cries for Kousuke to give her one. She is mean to Kousuke and calls him "Stupid", she is nice to Eyes. When she first met Ryoko, she used to tease her a little and the two never got along. Afterwards, they get along pretty well.
Spiral The Bonds of ReasoningEdit
Rio first appears in chapter eleven of Spiral. She is running away from a dog that wants her food, she trips and the dog takes off with her food. Rio then is sitting on the floor crying about it, being embarrassed, she runs off. She then is seen again by Ayumu and Hiyono when the teacher is yelling at her. She was blamed for a rock being throwed threw the window.
Ayumu settles it and shows it wasn't Rio. Later on, Rio tells him "Thank you", and runs off once again, but fails in the process. It is no too later on Rio kills Mr. Imazato, and Ayumu and Hiyono then search who the killer is. They know it was a Blade Child, due to the fact that could be the best reason for it, because Mr. Imazato knew about the Blade Children.
Rio then plains a way to bomb herself so she can throw out a couple of ribs, making Kousuke think she was doing it so Ayumu won't know she is one of the Blade Children. Due to the Blade Children are all missing one rib. Rio then creates a bomb in a stuff kitty. She brings it to the newspaper club and the bomb goes off, only hurting Rio.
Rio is then sent to the hospital. Ayumu then finds out that Rio is one of the Blade Children. He goes to the hospital where Rio finally tells the truth about who she is. Then they have their first little game with each other. To drink a cup of water with one having poison in it and the other doesn't. Ayumu first tastes the water and thinks there really was poison in it due to it being bitter. Though, Hiyono drunk the rest of it and proved that there was no poison in it.
Afterwards, Rio threatens to kill Hiyono after she says she was the one that killed the teacher. Though, Hiyono to her and Kousuke's surprise, she was recording them. The two try to get the tape back, but Ayumu gets it and leaves, with Hiyono being captured. When Rio and Ayumu have a another rematch, they both have to get the tape and Hiyono.
During the next match though, Ayumu wins instead of Rio and Kousuke. This is when Rio's ribs open up and she faints on Ayumu. She was then taken to the hospital again, where she comes out soon later. When Rio comes out of the hospital her, Kousuke, and Ryoko have a little battle with Kanon e Hilbert. They all get hurt, but don't die. They all go to the hospital afterwards.
Rio believes that she can be saved. In the end of Spiral, Rio drops out of school, and decides to work in Third-world countries, defusing land mines left over from war.
In the anime version of Rio, she still gets chased by the same dog that wants her food. Though, in this version, she never drops out of school, nor does she get to become that age. Though, in one episode her and Hiyono get kidnapped by hunters. They get rescued by Ayumu, Ryoko, and Kousuke.
Rio also appears in a story called Spiral Alive. This shows Rio, Kousuke, and Ryoko younger then what they are in Spiral The Bonds of Reasoning. During this story, this is the first time Rio meets Ryoko. Rio keeps smiling at her and being silly, and teasing her getting her mad. Rio is also seen with Kiyotaka. He spends her around, then he takes her somewhere with him and talks with her.
- Rio in the anime version is the youngest Blade Child, though in the manga it shows that Eyes is really the youngest, not Rio, and also in Spiral Alive, it shows Rio is older then Ryoko
- Rio is very smart, and knows how to get out of a bad situation
- She is the midget of the Blade Children, and appears to look like a 13 year old
- She is the one that created the bomb that looked like a turtle
- Rio knows how to create bombs, and yet gets many nicknames from people through out the series