Kenshin is the titular "Rurouni" (wanderer) and main character of the series. He is formerly known as the Hitokiri Battosai, a deadly man-slayer who slaughtered many men in the war before the Meiji era. Kenshin's fighting style is Hiten Mitsurugi-ryu, now an ancient study. With this dangerous sword style, he uses his Sakabato (A sword with a reversed edge) to restrain himself from killing anyone ever again, and renounces the title Hitokiri.
Source from Wikipeida