A farmer named Yozaemon owed thirty sacks of rice. He asked the magistrate for more time to pay. The answer was not patience, or negotiation, or even a beating. The magistrate — a man named Tanaka Sosuke — had Yozaemon's daughter-in-law arrested. She was nine months pregnant. He had her placed in a basket or cage and lowered into an icy winter river. She stayed there for six days and six nights. She gave birth in the water. She died there. The child died with her.

This was not the worst of it. Around the same time, on the same peninsula, officials were devising other entertainments for those who could not pay their taxes. The method was called mino odori (Mino Odori) — the straw raincoat dance. A tax defaulter would be dressed in a mino (Mino), the traditional straw raincoat worn by farmers in the rain, hands tied behind the back. The straw was set alight. The victim's desperate writhing as the fire consumed the coat — the officials found this amusing. A dance.

In another documented incident, a tax defaulter's daughter was stripped naked and tied to a post, where she was burned with torches while her father was forced to watch. At some point the father's mind broke. He killed the sheriff on the spot.

The Shimabara Peninsula had been Matsukura family territory since 1616. Matsukura Shigemasa, the patriarch, had inherited a domain still haunted by Christianity — the region around Nagasaki was one of the most heavily Christianized areas in Japan, the result of decades of Portuguese missionary work. Shigemasa pursued the persecution of Christians with extraordinary enthusiasm. Between 1627 and 1632, he oversaw the boiling alive of 188 Catholics in the volcanic springs of Unzen Jigoku — the Hell Springs — along with other prolonged torture methods designed to force apostasy. His son Matsukura Katsuie inherited the domain in 1630 and continued his father's policies, while also imposing crushing tax burdens on a population already strained by three consecutive years of drought and famine.

When the uprisings came in late 1637, they came fast. Armed groups of peasants killed magistrates and burned official buildings. The local violence coalesced into a full rebellion on December 17, 1637, when the magistrate Hayashi Hyozaemon was assassinated — the event traditionally counted as the formal start of the Shimabara Rebellion, or Shimabara no Ran.

The rebels' leader was Amakusa Shiro, a 16-year-old Catholic boy from the Amakusa Islands, believed by his followers to be a figure of miraculous power. He and the rebel forces, numbering in the tens of thousands, fortified the ruins of Hara Castle on the Shimabara Peninsula and prepared to resist.

The Tokugawa shogunate deployed 125,000 troops — the largest military mobilization of the Edo period — to besiege approximately 37,000 rebels barricaded in a ruined castle. The siege lasted nearly four months. When it ended in April 1638, nearly all inside were killed. An estimated 37,000 heads were taken and displayed. Amakusa Shiro was beheaded at age 17.

The consequences radiated outward for generations. The shogunate expelled the Portuguese from Japan in 1639 — their missionaries and traders had been associated with the Christian character of the rebellion. The policy of sakoku (Sakoku), national seclusion, was hardened into something close to permanent. Japan would remain effectively closed to the outside world for more than two centuries.

Matsukura Katsuie, whose family's cruelty had provided the kindling, was tried and publicly beheaded on August 28, 1638. This was extraordinary: daimyo were permitted the dignity of seppuku. To behead a daimyo like a common criminal was a declaration by the shogunate that what Katsuie had done — or more precisely, what he had allowed to happen in his domain — was beyond the bounds of acceptable failure. He was 40 years old. He was the only daimyo publicly executed in the entire 265-year span of the Edo period.

His father had boiled 188 people alive. His magistrate had drowned a pregnant woman in a river. One official's cruelty, multiplied across a starving population for a generation, produced a revolt that required 125,000 soldiers to suppress and permanently altered the trajectory of Japanese history. The Tokugawa peace was real, but it rested on instruments like Tanaka Sosuke — and on the assumption that the people beneath them had nowhere left to go.