Younger sister of Rally Cheyenne. Half Lucifer Hawk, she left Earth to live on Nemesis years ago and returned to kill her sister in volume 3 of the manga. Her heritage gives her powerful magic, but she does not seem to be her sister's equal. Rosa also fights with a whip.
Rosa appears to be two to four years younger than her sister in the few flashbacks to their childhood. In the present time (2028-30), the difference seems much greater. Her hair is a slightly darker purple than Ganossa's. One of her major motivations is a desire to escape her sister's shadow.
(Source: Wikipedia)