Katsushiro Okamoto
About
Of the samurai, Katsushiro's character evolves the most throughout the series. At first he is overcome with shock upon his first kill. Kirara is overcome with guilt for having brought him into a situation in which he is forced to take life, and pledges to support him even as he falls into darkness. Kambei and the other samurai soon teach Katsushiro that taking life is part of being a true samurai. By the last battle he can kill numerous enemies without flinching. Katsushiro takes a liking to Kirara early on in the series, attempting to protect her in numerous situations, and at one point asks her to come with him after he has a falling out with Kambei. He later returns to Kanna village after his solo journey as a much more mature and skilled samurai.
Katsushiro is one of the 3 surviving samurai following the final battle against the capital, and is shown post-battle to have gained significant wisdom and maturity from his experiences. His skills are improved enough by the end that Kambei even shows great respect towards him, and presents Katsushiro with his own katana. In the end he leaves the village to continue his samurai life.
(Source: Wikipedia)