Katsura Kogoro was the legendary young leader of the Chōshū Ishin-Shishi who, along with Ōkubo Toshimichi and Saigō Takamori, became one of the three key figures of the Meiji Restoration after they forged an alliance between former enemies Chōshū and Satsuma. After witnessing young Himura Kenshin's impressive performance in the Kiheitai, Katsura recruited the fourteen year-old swordsman into his service as a hitokiri in Kyoto and acts as the Battōsai's immediate superior during the Bakumatsu.

(Source: Rurouni Kenshin Wikia)