Kenshin Himura, originally named Shinta, is the central character of a story set in the Meiji period of Japan. He is a man of small stature, standing only 158 centimeters tall, with a slight build, red hair, and a distinctive cross-shaped scar on his left cheek. His appearance is deceptively gentle and youthful for a man of twenty-eight who was once one of the most feared warriors of his era.

His background is one of profound tragedy. As a very young child, his parents died of cholera, and he was soon after captured by human traffickers. When the traffickers were attacked by bandits, three older women who had been looking after him were killed while protecting him. He was then rescued by a man named Hiko Seijūrō, the thirteenth master of a powerful swordsmanship style known as Hiten Mitsurugi-ryū. Hiko took the boy in, gave him the new name Kenshin, meaning "Heart of the Sword," and began training him as the style's next successor.

During the violent Bakumatsu period, a young Kenshin left his master to join the Ishin Shishi, a group of revolutionaries fighting to overthrow the Tokugawa shogunate. His incredible skill earned him the legendary and dreaded title of Hitokiri Battōsai, the "Manslayer". In this role, he was a perfect assassin, known for his unmatched speed and lethal efficiency. However, his life as an assassin was marked by immense personal sorrow when he accidentally killed his first wife, Yukishiro Tomoe, a woman who had initially been sent to spy on him but had instead come to love him. Her death, combined with the violence he had already committed, left him with the cross-shaped scar on his face and a deep, unshakable guilt.

This traumatic event led to his transformation. After the Meiji Restoration ushered in a new era of supposed peace, Kenshin vanished. He re-emerged as a wandering swordsman, or rurouni, who had sworn a solemn vow never to take another life. To honor this vow, he wields a unique sakabatō, a katana with the blade on the reverse side, making it nearly impossible to kill with a standard slash. His primary goal is to atone for his past sins by helping those in need, offering protection and aid to the vulnerable citizens of a rapidly changing Japan.

His personality is a stark contrast to his past as a manslayer. In his daily life, Kenshin is soft-spoken, gentle, and almost childishly naive, often reacting with his trademark bewildered expression and the exclamation "oro" when surprised or confused. He is unfailingly polite, humble to a fault, and cheerfully takes on all the domestic chores of the Kamiya Dojo, such as cooking and laundry, as a way of repaying the kindness shown to him. Yet, when his friends or innocent people are threatened, his demeanor instantly changes. His eyes become sharp and glowing, and he reverts to the cold, hyper-competent fighting style of the Battōsai, though he continues to fight with the back of his blade. This duality is central to his character; he carries the burden of a killer while striving to live as a savior.

Throughout his journey, he forms a new family in Tokyo. The most important relationship is with Kamiya Kaoru, a young kendo instructor who invites him to stay at her dojo. Her unwavering belief in his goodness and her philosophy of the sword that protects life, or katsujinken, provide Kenshin with a place of peace and emotional healing. Their bond deepens throughout the series, and they eventually marry and have a son named Kenji. He is also joined by Sagara Sanosuke, a former soldier who becomes his best friend and loyal comrade, and Myōjin Yahiko, a young boy from a samurai family whom Kenshin mentors, eventually passing on his sakabatō as a symbol of a new, peaceful era.

His past continues to define his present through his relationships with former enemies and rivals. This includes a complex and grudging respect for Saitō Hajime, a former shogunate officer who now serves as a Meiji government police official. He also clashes with Shinomori Aoshi, the former leader of the Oniwabanshū, who seeks to defeat Kenshin to prove his strength, though they later become allies. His most significant personal conflict arises with Yukishiro Enishi, the younger brother of his deceased wife Tomoe, who seeks revenge for his sister's death.

As a fighter, Kenshin is a master of the Hiten Mitsurugi-ryū, a style focused on incredible speed, acrobatic maneuvers, and precise battōjutsu (sword-drawing techniques). His ultimate technique, the Amakakeru Ryū no Hirameki, is a super-speed battōjutsu that surpasses his already god-like speed, creating a vacuum that pulls the opponent in before delivering the finishing blow. Other notable techniques include the Kuzuryūsen, an attack that simultaneously strikes the nine vital points of the body, and the Ryūmeisen, a god-speed sheathing technique that creates a supersonic wave to disrupt the opponent's balance. Throughout the story, Kenshin undergoes a crucial character development. He moves from a state of being a wandering loner, paralyzed by past guilt, to a man who builds a home and fights not just for atonement, but to protect the precious people and peaceful future he has found in the new era.