Not much is known about Rose beyond the fact that she is a young dragon, and thus still unable to change her form. When she is first released from the case, the crime syndicate "Fang" was transporting her. She does not know how to speak and can only say Ryuuji's name, but soon picks up a few words (mostly learning from TV and Eriko). Since she could not communicate, or didn't know her name, Ryuuji gives her the name Rose because the dragon scales on the back of her left hand look kind of like a rose. Rose is intrusive towards nearly everyone, except Ryuuji to whom she clings so much to that she will sleep beside him in his bed.

(Gathered from Wikipedia)