Himura Kenshin (緋村 剣心 Himura Kenshin?) is a former legendary assassin known as "Hitokiri Battōsai" (人斬り抜刀斎?). At the end of the Bakumatsu, he becomes a wandering samurai, now wielding a sakabatō (逆刃刀? lit. "reverse-blade sword"), a katana that has the cutting edge on the inwardly curved side of the sword, thus being nearly incapable of killing. Kenshin wanders the countryside of Japan offering protection and aid to those in need, as atonement for the murders he once committed as an assassin. In Tokyo, he meets a young woman named Kamiya Kaoru, who invites him to live in her dojo despite learning about Kenshin's past. Throughout the series, Kenshin begins to establish lifelong relationships with many people, including ex-enemies, while dealing with his fair share of enemies, new and old. Through these encounters and relationships, Kenshin begins to find true atonement for his past enabling him to fully conquer his "Battōsai" nature.
Kenshin desires to protect every individual from danger without harming others. Formerly known as "the strongest hitokiri," Kenshin is the main target of many old enemies and people who want to gain his title, thus he avoids letting others get too close to him personally for their own protection. However, he eventually begins relying on his friends, allowing them to fight alongside him. He also has a rivalry with the ex-Shinsengumi member Saitō Hajime since the Bakumatsu. Although they become partners in the series, they both know that one day they will finish their duel. After the end of the Jinchu arc, Kenshin challenges Saitō to end the rivalry, but Saitō refuses to fight since Kenshin is different from the time they were enemies.
Throughout the series, a young woman named Kaoru develops strong romantic feelings for him, and he also comes to love her. Despite his feelings, he is constantly haunted by the wrongs committed in his past, and believes he does not deserve happiness. However, as he notes how Kaoru would feel if he dies, Kenshin decides not to leave her and regains a desire to survive.
If he is not able to protect his loved ones, he begins to shift into his "Hitokiri Battōsai" personality, and takes extreme measures in order save others, caring little for the well-being of his opponents. However, Kenshin avoids changing his personality, swearing that he will never kill, and will try to avoid the deaths of as many people as possible.
Kenshin is a practitioner of the Hiten Mitsurugi-Ryū (飛天御剣流? lit. "Flying Heaven Honorable Sword Style"), also referred to in the series as "Ultrasonic Sword Style", a fictional ancient sword art. Kenshin's mastery of the style allows him to possess superhuman speed and reflexes, study and predict his opponent's movements in battle, as well as perform many powerful sword techniques. Among several of his Hiten Mitsurugi-Ryū and battōjutsu skills, Kenshin can utilize Shinsoku (神速? lit. "God-speed"), which allows him to quickly overpower and dispatch opponents with his sword before they have time to react. Although most of his techniques were originally intended to have deadly effects, Kenshin fights using his sakabatō, a katana that has the cutting edge on the inwardly curved side of the sword (in contrast to a normal katana, where the outwardly curved side of the sword is sharp, while the inwardly curved side of the sword is blunt), since he desires not to kill anyone.
When Kenshin decides to continue his training to defeat Shishio Makoto, he learns the Kuzu-ryūsen (九頭龍閃? lit. "Nine-headed Dragon Strike"), which simultaneously deals nine strikes to the fundamental targets of swordsmanship, making guarding and dodging virtually impossible. The Kuzu-ryūsen, however, is a byproduct used for the initiation in learning Amakakeru Ryū no Hirameki (天翔龍閃? lit. "Heavens Bridging Dragon Spark"; Viz translation - "Dragon Flight of Heaven"), a Hiten Mitsurugi-Ryū battōjutsu that surpasses the speed of the Kuzu-ryūsen. The secret behind the technique lies in an additional step with the left foot which adds instantaneous acceleration and weight to the sword. In addition, if the initial strike is avoided or blocked, the force of the unusually fast slashing motion displaces the air around it, generating a vacuum in its wake and sucking the opponent in; as this happens, the body is spun around for a second strike, with the previous action adding force and momentum to the swing, making the subsequent strike far stronger.