|Spoiler Alert: This page contains spoilers. Read at your own risk.|
|Full Name||Lucas Rosen|
|Occupation||Former Rosen Family Head Successor|
|Novel||SS, Temptation of Rose (Mentioned)|
Lucas Rosen (ルーカス・ローゼン) is a member of the Rosen Family. He is the son of Bastian Rosen, the brother of the current Rosen Family Head, the father of Anna Rosen Katori, and grandfather of Chiba Erika. 
Even though he was reputed to be the most outstanding among his siblings, he was removed as a candidate to succeed his father as Family Head after it was discovered that he helped in the plot that allowed Georg Ostburg to flee during a terrorist incident in the United States when Lucas was fourteen years old and had setup for Georg to be his bodyguard. 
Ties to him were cut when he eloped with a Japanese women (Maiden name: Katori) and abandoned his fiancée that was chosen for him. This caused the Rosen trouble within European social circles, which allowed Maximilien Device the chance to do business in Europe. Though, because of the close ties the Rosen have with the German government and military, they were unable to expand into the market, in Japan.