The "midget" of the Blade Children group, she resembles a 13 year old child rather than her actual age, 16. Rio may seem small, but she is actually older then both Kousuke and Ryoko, as revealed in Spiral Alive, and the Bonds of reasoning manga. Although Rio appears to be the most innocent of the Blade Children with her cherubic features and size, she is actually very shrewd and calculating, and is one of the more dangerous of the blade children. Rio knows how to create bombs, devise difficult plans and kill those she considers her enemies. She is extremely intelligent and is able to escape from any sticky situation, no matter how small or tight it is. She is very straight-forward and has a crush on Eyes because he gives her 'netted pattern' melons (her favorite food). Like Kousuke, she will not hesitate to kill people if she has to.
(Source: Wikipedia/manga)