Code Geass : Shikkoku no Renya

A fourth manga adaptation, Code Geass: Tales of an Alternate Shogunate (幕末異聞録 コードギアス 反逆のルルーシュ Bakumatsu Ibun Roku Kōdo Giasu Hangyaku no Rurūshu?), was serialized in Kerokero Ace. Set in an alternate 1853, with arrival of Britannia's Black Ships appear in the harbor of Uraga and Lelouch Lamperouge (琉々朱・爛縁侍 Rurushu Ranperuuji?) as the commander of the Shogunate's military counterinsurgence brigade known as the Shinsengumi, which fights the Black Revolutionaries (黒の騎士団 Kuro no Kishidan?), a rebel group led by a mysterious masked individual known as Rei (零 lit. Zero?) (these two organizations turn out to be one and the same, seeking to combat influences of Britannia). Geass is the ability to call upon and summon the armored entities referred to as Knightmares (ナイトメア?), of which Lancelot (ランスロット?) is one. (Taken from wikipedia)