Three Kingdoms counterpart: Liu Bei
Birthday: June 23
Horoscope: Cancer
Age: 18
Height: 160 cm
Blood Type: B
Three Sizes: B-96 W-61 H-92
School: Seito's Academy, 2nd Year
Toushi Rank: E-Rank
Dragon: Rairyuu (Lightning Dragon)

Manga
A clutzy, ditzy bespectacled bookworm with seemingly no combat skills. She can't even swim. In the viewpoint and humor of the one who did the "English Adaptation", a fear of homosexuals, wondering if she is homosexual herself, and convinced that Kanu and Chouhui are lesbians who are attracted to her, was added to the English version. That isn't present in the original JPN version. Ryuubi is destined to be a great leader but is presently too timid and carefree to become one. However, she is still more than willing to do her best for her friends. She is best friends with Chouhi and possesses the most destructive dragon seen, which is so evil that it radiates enthropic energy and nearly made her disembowel herself before Ryomou, Chouhi, and Kanu managed to stop her, resulting in all of them being critically wounded. She seems unaware of this and is prone to occasional highly destructive out-bursts when her dragon rouses. These outbursts happen when Ryubi sees her friends get hurt in battle.

Anime
The initial difference is that the timing of her first dragon possession is different. The first time she is overwhelmed by her dragon in the manga was three years before the start of the manga. In the anime, it happens during the second series. When Kanu was forced to surrender to Sousou, her determination to rescue Kanu has her slowly gaining control of her dragon's powers. She realised that her school had to go into battle with Nanyo and Kyosho in order to finally end the conflict. Although she was targeted by many toushi in the battle, she was capable of protecting herself. Kanu's return gave Ryuubi more encouragement. She was almost strangled to death by Sousou but was saved by the returning Hakufu. Both Ryubi and Hakufu teamed up to destroy Sousou and win the battle for Seito and Nanyo. She is now back to her normal book-reading self.

(Source: Wikipedia)