You may want to consider
Rurouni Kenshin: Tsuiokuhen, the OAV prequel to the Rurouni Kenshin anime series. The four-part OAV was re-edited into a feature-length movie. It is far darker in tone than the series and, in my opinion, it's a much more mature work than both the anime and the original manga, which were too cartoonish and shounen for my tastes.
The story traces the origins of the wanderer Rurouni Kenshin, how he became a dreaded killer in a time of social and political upheaval, and how he eventually renounced his mission as an assassin, though at tremendous personal cost. The prologue of the movie itself seldom fails to reduce me to tears.