Rurouni kenshin is a manga about a samurai who used to he an assassin in a civil war and after that he decide to compensate his crimes by renouncing to kill people and helping them. There’s a character who especially reminds me to Kylo; Aoshi. He was a former evil guy that came to the good side but never became good. He attacked his adoptive father and stabbed him 42 times, before turning good. He stay with the good people for a girl who loves him, Misao. All the manga is about redemption.