The Okamoto Daihachi Scandal: Corruption, Forgery, and the End of Christian Japan

Chapter One

The Pretext

By 1612, Tokugawa Ieyasu, the retired shogun, still the most powerful man in Japan despite having formally ceded the title to his son Hidetada, had spent a decade watching the Christian problem with the careful, unblinking patience of a man who had built an empire by knowing exactly when to strike. He had tolerated the Jesuits because they were useful, their entanglement with the Portuguese silk trade made them commercially indispensable, and the Dutch and English alternatives were still establishing themselves. He had tolerated the Christian daimyō because dismantling them prematurely risked destabilising the fragile peace he had imposed after Sekigahara. He had tolerated the 300,000 converts because they were, for the moment, quiet.

But he had never trusted any of them. William Adams, his English advisor, had been whispering for years that the Catholic priests were agents of Iberian imperialism. The Dutch reinforced the message from their trading post at Hirado. The Spanish Philippines loomed to the south, a living example of what happened when missionaries and soldiers operated as a coordinated system. And within his own administration, within the inner circle of his own most trusted councillor, a Christian secretary was about to commit a crime so brazen, so stupid, and so perfectly timed that it would hand Ieyasu the justification he had been waiting for.

The scandal that followed was, in the strict sense, a sordid affair of bribery and forgery involving two men of middling importance. In its consequences, it was one of the most significant political events of the seventeenth century.

Chapter Two

The Galleon in the Harbour

The chain of events that produced the Okamoto Daihachi scandal started not in a government office but in Nagasaki harbour, in the winter of 1609–10, with a Portuguese carrack called the Madre de Deus.

The backstory was a brawl. In Macau, the Portuguese enclave on the South China coast that served as the staging point for the annual Japan trade, a violent altercation had erupted between Portuguese sailors and the Japanese crew of a red-seal ship owned by Arima Harunobu, one of the most powerful Christian daimyō in Kyushu. Several Japanese sailors were killed. Arima, furious, reported the incident to Ieyasu and requested to be notified when the next Portuguese vessel entered Japanese waters.

The vessel that arrived was the Madre de Deus, also known as the Nossa Senhora da Graça, commanded by Captain-Major André Pessoa, who had served as governor of Macau during the original fight. This was not a coincidence that Arima was inclined to overlook. He petitioned Ieyasu for permission to attack the ship. Ieyasu, who had already confirmed with the Dutch and Spanish that alternative sources of European goods were available, granted it.

In early 1610, Arima personally commanded the Japanese forces that surrounded and assaulted the carrack in Nagasaki harbour. Pessoa fought back with a determination that bordered on the suicidal—the Portuguese, whatever their other qualities, did not lack for nerve—but the situation was hopeless. Rather than surrender his ship, Pessoa ignited the powder magazine. The explosion destroyed the Madre de Deus, killed Pessoa and roughly two hundred crew members, and sent three thousand piculs of silk and two hundred thousand cruzados’ worth of silver to the bottom of the harbour.

Arima Harunobu considered his role in this spectacle a great service to the shogunate. He had avenged the insult to his men, eliminated a Portuguese captain who had presided over the killing of Japanese sailors, and demonstrated his loyalty to the Tokugawa regime with an act of conspicuous military violence. He expected to be rewarded. Specifically, he expected the return of ancestral territories in Hizen province, including the small fortress of Isahaya, that his family had lost to the neighbouring Matsura clan during the civil wars of the preceding century.

The reward did not materialise. And Arima, consumed by the conviction that he was owed, began looking for someone who could make it happen.

Chapter Three

The Man in the Middle

He found Okamoto Daihachi. Okamoto was, on paper, a perfect intermediary. He was a Christian, which gave him a confessional bond with Arima, a fellow believer. He was a senior secretary in the household of Honda Masazumi, one of Ieyasu’s most trusted councillors, which gave him proximity to power. And he was, as events would demonstrate, a man of flexible morals and considerable greed, which gave him a motive to exploit the situation.

Arima’s calculation was straightforward: if Okamoto could use his access to Honda to press Arima’s land claim before Ieyasu, the ancestral territories would be restored. To ensure Okamoto’s enthusiastic cooperation, Arima paid him massive bribes—the sources describe the sums as enormous without specifying the exact figures, which probably means they were large enough to embarrass everyone involved.

Okamoto accepted the bribes. He had no intention of pressing the case.

What followed was a con of almost elegant simplicity. Okamoto pocketed the money, told Arima that the petition was proceeding through the proper channels, and, when Arima pressed for evidence of progress, produced forged documents bearing counterfeit seals of Tokugawa Ieyasu himself. The fabricated letters patent indicated that the shogunate had granted the coveted lands to Arima. The forgery was good enough to satisfy a man who desperately wanted to believe it was real.

Arima believed. He waited. The lands did not appear.

When Arima grew impatient and demanded to know why the supposedly granted territories had not actually been transferred, Okamoto improvised. He told Arima that the petition had originally been approved but was subsequently revoked due to the malicious interference of Hasegawa Sahyoe, the Tokugawa shogunate’s governor of Nagasaki—a man who was both a staunch opponent of Christianity and a bitter personal enemy of Arima’s.

This was a lie built on a foundation of real hatred. Arima despised Hasegawa. Hasegawa had long coveted Arima’s fief. The two men were natural enemies, separated by religion, politics, and competing claims to influence in Kyushu. When Okamoto told Arima that Hasegawa was responsible for sabotaging his land grant, he was pouring accelerant on a fire that was already burning. Arima decided to have Hasegawa killed.

Chapter Four

The Unravelling

An assassination plot against a shogunal governor was not a private grievance. It was treason. Arima was now implicated in bribery, conspiracy to murder a government official, and, through Okamoto, the forgery of the retired shogun’s personal seal—an act roughly equivalent to counterfeiting the signature of the state itself.

The scheme collapsed when Arima, frustrated by the continued non-materialisation of his lands, bypassed Okamoto entirely and appealed directly to the shogunate, or to Honda Masazumi himself, to finalise the transfer. At that point, the forgery was discovered. The documents bearing Ieyasu’s seal were examined and found to be counterfeit. Okamoto’s entire fabrication came apart.

When confronted, Okamoto, facing execution for forgery, retaliated by exposing Arima’s assassination plot against Hasegawa. Arima, in turn, had no defence: the bribes were documented, the murder conspiracy was real, and the forged seals were in his possession. Both men had destroyed each other.

The full scope of the affair now lay exposed before the shogunate: a Christian daimyō had bribed a Christian official inside the inner circle of one of the shogun’s most trusted advisors. The Christian official had forged the shogun’s own seal. The Christian daimyō had plotted to assassinate the shogunal governor of Nagasaki. Every principal in the conspiracy was a baptised Catholic. The affair had penetrated the administrative core of the Tokugawa state. For Ieyasu, it was not merely a scandal. It was confirmation.

Chapter Five

Two Executions

Okamoto Daihachi was condemned to death. Because his Catholic faith prohibited self-killing, he refused the option of seppuku, the ritual suicide that was, for a samurai, the honourable exit from an impossible situation. The refusal itself was a political statement, whether Okamoto intended it as one or not: here was a man choosing a foreign God’s prohibition over the fundamental social code of the warrior class. He was burned alive at the stake in April 1612, in full view of his wife, who had initially been condemned to share his fate but was spared at the last moment.

Arima Harunobu, Dom Protásio, one of the most prominent Christian lords in Japan, sponsor of Jesuit seminaries, patron of the Church, was stripped of his domain and sent into exile in the remote province of Kai. He was subsequently sentenced to death and ordered to commit seppuku. Like Okamoto, he refused on religious grounds. He was beheaded by one of his own retainers in June 1612, roughly two months after Okamoto’s execution.

Two Christians, executed within weeks of each other, both refusing the samurai death because the samurai death was a mortal sin. The symbolism was lost on no one. The message—to Ieyasu, to the shogunal council, to every daimyō in Japan—was that Christianity created men whose ultimate loyalty was not to the social and political order but to an authority beyond the reach of the state. This was precisely the fear that Hideyoshi had articulated in his 1587 edict, that the Jesuits had spent decades trying to allay, and that the Okamoto Daihachi scandal now proved with devastating specificity.

Chapter Six

Honda’s Game

There is a footnote to the scandal that illuminates how the Tokugawa system actually worked.

Honda Masazumi, the powerful councillor whose own secretary had committed the crimes, was not implicated in the bribery, the forgery, or the assassination plot. The evidence indicates that Okamoto acted entirely on his own—a rogue agent who exploited his proximity to power for personal enrichment. Honda was, in the strict sense, innocent.

He was also, in the political sense, vulnerable. The scandal had occurred inside his household. His judgement in employing Okamoto was, at minimum, questionable. The affair was a stain on his reputation that rivals within the shogunal administration could exploit.

Honda’s response was characteristically Tokugawa: he deflected. Rather than absorb the damage, he redirected suspicion toward his political enemies—specifically the powerful Ōkubo family, including his rival Ōkubo Tadachika and the notoriously corrupt gold commissioner Ōkubo Nagayasu. Honda promoted the narrative that the Ōkubo faction, not his own household, harboured the real Christian sympathisers and subversive elements within the administration. The strategy worked. The Ōkubo fell from power in scandals of their own shortly afterward, and Honda survived.

The Okamoto Daihachi affair was, at one level, a story about Christians. At another level, it was a story about the internal factional politics of the Tokugawa state, in which Christian identity was a weapon that could be wielded against rivals as easily as it could be deployed against foreigners. The persecution that followed the scandal served the shogunate’s stated goal of eliminating a foreign religion.

Chapter Seven

The Hammer Falls

The scandal’s immediate consequence was a decree, issued in 1612, prohibiting the practice of Christianity within the direct shogunal domains—Sunpu, Edo, Kyoto, and Nagasaki. Franciscan and Jesuit churches in the major cities were suppressed or demolished. In the Arima domain, Harunobu’s son and successor Naozumi, baptised as Miguel, now frantically apostatising to save his position, was ordered to crush the Christian communities his father had spent decades building.

But the 1612 decree was a preliminary measure. The definitive blow came in January 1614, when Ieyasu ordered the Zen monk Konchiin Sūden to draft a comprehensive, nationwide ban—the “Statement on the Expulsion of the Bateren”. The document declared Japan the “Land of the Gods”, branded Christianity a “pernicious doctrine” designed to overthrow the government, and set in motion the machinery of persecution that would grind on for the next three decades.

The 1614 edict triggered a cascade of consequences. Hundreds of missionaries—Jesuits, Franciscans, Dominicans, Augustinians—were rounded up in Nagasaki and deported to Macau and Manila. Prominent Japanese Christian leaders were expelled with them, including the most famous Christian daimyō of all, Takayama Ukon, Dom Justo, who chose exile over apostasy and died in Manila the following year. Every Catholic church, monastery, and seminary in the country was ordered demolished. The terauke system, requiring every Japanese citizen to register at a local Buddhist temple, whose priests were tasked with conducting annual inspections to identify hidden Christians, transformed the Buddhist clergy into a nationwide apparatus of state surveillance. Daimyō across the country were commanded to force their Christian subjects to renounce their faith, and the authorities began deploying the public executions and tortures that would escalate, under Ieyasu’s successors, into one of the most systematic religious persecutions in early modern history.

Chapter Eight

The Seeds of Shimabara

The scandal’s longest fuse led to a castle on the Shimabara Peninsula.

When Arima Harunobu was executed and his domain transferred to his son Naozumi, the young daimyō faced an impossible task: eradicate Christianity in a region where it had been the majority faith for decades. Naozumi tried. He persecuted his own subjects with a brutality driven by the knowledge that his survival depended on the shogunate’s satisfaction. He was not brutal enough. In 1614, the shogunate transferred Naozumi to a new fief at Nobeoka in Hyūga province, removing the Arima family from their ancestral lands entirely.

The Christian population of the Shimabara Peninsula was left behind—leaderless, heavily taxed, disenfranchised, and seething with a resentment that had been building since the day their lord was beheaded for refusing to commit seppuku. The new lords who replaced the Arima were not Christian. They were not sympathetic. They were, in the case of Matsukura Shigeharu, spectacularly cruel—a daimyō who would impose taxes so ruinous and enforce them with torture so sadistic that his own subjects would eventually rise in the only full-scale military rebellion the Tokugawa shogunate would face in two and a half centuries of rule: The Shimabara Rebellion of 1637–38.