Imagine being ten years old when your parents are murdered. Imagine spending the next twelve years of your life — your entire adolescence and young adulthood — crossing Japan in pursuit of the man who killed them. Imagine finally finding him. Imagine killing him.

Now imagine being arrested for it.

This was Usui Rokurō's story, and it is the story that the Meiji government's Decree No. 37 — issued on February 7, 1873 — made possible. Not the murder. The arrest.

For most of Japanese history, what Usui did would not have been a crime. It would have been a duty. 仇討ち (Katakiuchi) — the vendetta, the avenging of a murdered parent or elder sibling or lord — was one of the most culturally central acts in the samurai world. Its practitioners were not criminals; they were heroes. Its failures were not unfortunate; they were shameful. A samurai son who did not avenge his father's murder was a coward and an outcast. The code of honor that defined the warrior class made vengeance not merely permissible but obligatory.

The Tokugawa shogunate (徳川幕府, Tokugawa Bakufu), ever systematic, had found a way to manage this obligation without abolishing it. During the Edo period (江戸時代, Edo Jidai), an avenger could apply for a kataki-uchi jōkyosho (仇討ち許可書, katakiuchi jōkyosho) — literally a 'vendetta permit' — from domain authorities. The permit named the target, acknowledged the legitimacy of the pursuit, and imposed certain rules: you could not kill an innocent bystander, you could not pursue the vendetta in certain restricted areas, you had to conduct the killing in a manner befitting your station. The bureaucracy made vengeance orderly. The culture made it glorious. Famous vendettas were dramatized in kabuki (歌舞伎, kabuki) theater; crowds wept at the loyalty and suffering of avengers. The Forty-Seven Rōnin (四十七士, Shijūshichi-shi), who spent years secretly planning revenge for their lord's death before carrying it out in 1703, became the defining image of samurai devotion — celebrated in plays, paintings, and stories for generations.

The shogunate never considered abolishing katakiuchi. It was too embedded in the social contract of the warrior class, too central to the meaning of 義理 (giri) — the web of obligation that kept the samurai system functioning. To end the vendetta would have been to say that a samurai's duty to his murdered father was less important than the state's administrative convenience. The shogunate was unwilling to make that argument.

The Meiji government had no such hesitation.

On February 7, 1873 — just thirty-seven days after Japan officially adopted the Gregorian calendar as part of its modernization drive — the Grand Council of State issued Decree No. 37, the Katakiuchi Kinshirei (仇討ち禁止令, Katakiuchi Kinshirei): the Prohibition on Vengeance. Its language was deliberate and philosophically radical. 'The right to punish a murderer lies with the Government alone,' the decree stated. Private vengeance was not just illegal; it was described as a 'usurpation of public authority' — an act of lèse-majesté against the modern state. The framing was crucial. The Meiji government was not merely changing the rules of a practice; it was declaring that the entire moral framework that made the practice honorable was wrong.

The original proposal by the Minister of Justice had recommended the death penalty for avengers. The final decree softened this — no avenger was ever executed under it — but the principle was unambiguous. The government understood it was not simply legislating behavior. It was legislating values, inverting a moral order that had defined the warrior class for centuries.

The decree passed with little immediate organized resistance. The samurai class had already been absorbing one blow after another: the abolition of domains (廃藩置県, haihan chiken) in 1871 had stripped daimyo of their territories. The elimination of samurai stipends (秩禄処分, chitsuroku shobun) would come in 1876, the same year the sword ban (廃刀令, haitōrei) took effect. Each decree dismantled one more element of samurai identity. The Katakiuchi Kinshirei struck at something deeper than territory or income or the right to carry weapons — it struck at the samurai's self-image as the guardian of an honor code that superseded ordinary law.

Some men were not persuaded by legislation.

Usui Rokurō had been ten years old in 1868 when his parents were killed. He spent twelve years tracking the killer across Japan — pursuing a vendetta that, when he began it as a child, was still culturally legitimate, still the kind of act that kabuki audiences cheered. By the time he completed his quest in 1880, the world had changed around him. He killed the man who had killed his parents. He was arrested, tried, and sentenced to imprisonment.

The courts handled him carefully. No execution — the government did not want a martyr. Just prison, and the cold assertion that the state alone held the right to kill. Usui Rokurō is generally considered the last known practitioner of katakiuchi in Japanese history. He had pursued an obligation formed in the old world and completed it in the new one, and the new one put him in jail for it.

The Forty-Seven Rōnin, had they acted in 1873, would have faced the same fate. That was not an accident. The Meiji government knew exactly which stories it was overwriting.