However, the narrative tension arises from the fragility of this vow. Kenshin is a man suppressing a deeply ingrained killer instinct. When pushed to the brink, his eyes change color—from warm violet to cold, piercing amber—and the "Battosai" persona threatens to resurface. Kenshin’s battle is not just against external villains, but an internal struggle for his own soul. While the premise sounds dark, The Rurouni Kenshin is often surprisingly lighthearted, owing much to its secondary cast. Kenshin wanders into Tokyo and is taken in by Kaoru Kamiya, the young master of a struggling swordsmanship school.

The Tokugawa Shogunate had fallen, ending over 200 years of feudal isolation. Japan was racing toward modernization, adopting Western technology, clothing, and governance. It was a time of progress, but also a time of deep spiritual and social dislocation. The samurai class was being dismantled; the carrying of swords was banned.

As the legendary "Hitokiri Battosai" (the Manslayer), Kenshin was a political assassin whose sword helped topple the Shogunate. But the violence left him hollow. At the start of the story, he has taken a vow of pacifism: katsujinken (the sword that gives life), opposing satsujinken (the sword that takes life). This is symbolized by his sakabato —a reverse-blade sword. The cutting edge is on the back of the blade, allowing him to defeat enemies without killing them.