Code Geass - Soubou no Oz

Code Geass: Oz the Reflection is a spinoff published in Hobby Japan magazine and Kadokawa Shoten's Newtype Ace magazine. It tells a story from the viewpoints of two different protagonists.
The story takes place between the first and second seasons of the TV anime and is told from two perspectives. The photo story in Hobby Japan centers around Orpheus Zevon (Jivon), a young terrorist with the Knightmare Frame (KMF) Byakuen who is in pursuit of his lover's killer. The manga in Newtype Ace revolves around Oldrin Zevon, a girl in the Britannia Empire's anti-terrorist unit Glinda Knights who pilots the KMF Lancelot Grail.
(Source: Code Geass Wiki)