The Black Rose is a dashing, handsome and mysterious thief who steals from the rich and gives the stolen wealth to the poor, since he believes that all the wealthy people are frivolous and self-centered. He is very well-loved by the crowd, and famous among the journalists. His trademarks are his black costume with cape, mask, and calling card that he uses to taunt his future victims. He crosses paths with Nadja several times during her travels with the Dandelion Troupe; she is at first enraged by his dry wit and exploits, but later learns his motives and starts to empathize more with him.
The Black Rose's true identity is revealed mid-way in the series. His true name is Keith Harcourt, and he is the older twin brother of Francis, who walked away from his family after he finished his schooling at age 15. He shares his twin's desire to help the poor, but is far more cynical and disenchanted, since he thinks that 'noblesse oblige' is insufficient. The death of their mother had an influence; while the more innocent Francis saw only Countess Harcourt's kinder side, Keith saw her secret unhappiness upon being a bird in a gilded cage. Nadja's love of freedom touches him so much that he appoints himself as her protector after he rescues her from Rosso and Bianco.
In the manga Keith doesn't exist, so Francis really is the thief Black Rose.