The manga series Rurouni Kenshin features a large cast of fictional characters created by Nobuhiro Watsuki. Set in Japan during the Meiji period, several of the characters are real historical figures who interact with the fictional characters.

The story begins in 1878 and follows a pacifist wanderer named Himura Kenshin, who was previously an assassin known as "Hitokiri Battōsai" working for the Ishin Shishi during the Bakumatsu period. After helping Kamiya Kaoru, the instructor of a kendo school in Tokyo, in defeating a criminal, he is invited by her to stay at her dojo. During his stay in Tokyo, Kenshin befriends new people including Myōjin Yahiko, a young child descendant from a samurai family who starts training under Kaoru, Sagara Sanosuke, a former Sekihō Army cadet who enjoys fighting, and Takani Megumi, a doctor involved with the illegal drug trade. He also encounters old and new enemies whose ambitions cause Kenshin to return to fighting, this time to protect the innocent.

Himura Kenshin (緋村 剣心) is a former legendary assassin known as "Hitokiri Battōsai" (人斬り抜刀斎) (rendered as Battousai the Manslayer in the Media Blasters English anime dub, as Battousai: The Slasher in the Sony English dub.) At the end of the Bakumatsu, he becomes a wandering samurai, now wielding a sakabatō, a katana that has a structure in which the blade and ridge are struck in the opposite direction to a regular katana, so if it is used normally, it will always be in a ridged state and will have much less killing power. Kenshin wanders the country offering protection and aid to those in need as atonement for the killings he once committed as an assassin. He meets a young woman named Kamiya Kaoru in Tokyo, who invites him to live in her dojo despite learning about Kenshin's past. Throughout the series, Kenshin begins to establish relationships with many people, including ex-enemies, while dealing with his fair share of foes, new and old.

Kamiya Kaoru (神谷 薫) is the instructor of a kendo school in Tokyo called Kamiya Kasshin-ryū. All of its students leave when many people are killed by someone claiming to be Hitokiri Battōsai and a practitioner of Kamiya Kasshin-ryū, damaging her school's reputation. The real Battōsai, now wandering pacifist Himura Kenshin, saves Kaoru from this murderous impostor. Kaoru invites Kenshin to stay at her dojo as she notes that he is a gentle person instead of a hitokiri. As the series continues, Kaoru develops strong romantic feelings for Kenshin, who is constantly haunted by his past deeds and believes he does not deserve happiness.

Myōjin Yahiko (明神 弥彦) is an orphan from a samurai family who was forced to work as a pickpocket to repay the debt he had presumably owed, as his parents died before they could repay it. When Himura Kenshin rescues him, he decides to grow up to be just like Kenshin. But because of his strong beliefs, Kenshin will not teach the sword style he had learned. Therefore, Kenshin arranges for Yahiko to be trained in Kamiya Kasshin-ryū by Kamiya Kaoru. As the series progresses, Yahiko becomes skilled at swordsmanship and faces many opponents.

Sagara Sanosuke (相楽 左之助) is a former member of the Sekihō Army. When the group was destroyed by the Meiji government, he became a fighter-for-hire to calm his anger by fighting. During his introduction in the series, he encounters the wanderer Himura Kenshin, who easily defeats him and can convince him to stop his mercenary work and instead start protecting people. Sanosuke becomes Kenshin's best friend and his partner in most of their fights.

Takani Megumi (高荷 恵) comes from a famous family of physicians from the Aizu region.^[ch. 19] She became the assistant to a Tokyo physician who had created a deadly new form of opium. When the doctor was killed, she was forced to make the new opium for corrupt industrialist Takeda Kanryū for the past three years.^[ch. 19] After being freed and stopped from committing suicide by Kenshin and Sanosuke, she becomes a doctor to atone for her past misdeeds.^[ch. 29] She has a wicked sense of humor and enjoys flirting with Kenshin to make Kaoru jealous (both Kaoru and Sanosuke refer to her as a "vixen" and in the manga vixen ears appear whenever she indulges in her sense of humor), but helps Kaoru come to terms with her feelings towards Kenshin. She is loyal to her friends and is always there to heal their wounds, especially Sanosuke, whom she often cautions about fighting. At the end of the series, she leaves Tokyo to open a clinic in Aizu.^[ch. 252]

Nobuhiro Watsuki created Megumi as a "mature woman" but had no specific model in mind. In the first Rurouni: Meiji Swordsman Romantic Story one-shot, Megumi, Kaoru, and Yahiko were siblings. Despite this version and her final version in the main series being so different, Watsuki said they have the same spirit and are not so unalike. Although he admitted the one-shot's version of Megumi had a "lighter quality" because of her small role, he, therefore, gave her a more "earthy quality" in the main serial so she could make an impression. By the time of the publication of Rurouni Kenshin volume four, Watsuki felt disappointed as she did not turn out nearly the way he wanted. However, because she is entertaining to draw and is the only woman Kaoru can interact with, he planned to have Megumi frequently appear as a secondary character. Watsuki's used the young grandmother from Takeshi Obata's Cyborg Jii-chan G [ja] as the design model for Megumi. Her story arc has "redemption for her crimes" as its theme, and the author wanted to express Kenshin's determination through Megumi. Megumi came in fourteenth place in the series' second character popularity poll, and fifteenth in the third. She is portrayed by Yū Aoi in the live-action films.