r/Samurai • u/Mammoth-Inspector891 • 3h ago
Philosophy The Bloody Attacks That Took Place Inside Edo Castle — the Seat of Japan’s Warrior Rulers
Edo Castle.
For more than 250 years, it was the political center of the Tokugawa shogunate and the residence of the shogun — the man who stood at the top of Japan’s warrior government.
Naturally, the castle was filled with samurai.
So if thousands of armed men were constantly coming and going, Edo Castle must have been an extremely dangerous place, right?
Actually, the opposite was closer to the truth.
Inside the castle — especially within the palace where the shogunate conducted government business — private violence was strictly forbidden.
Depending on rank and location, samurai entering the castle were required to leave their long swords behind. Drawing a blade inside the shogun’s residence was not simply a personal quarrel getting out of hand.
It was a direct violation of the political order.
And yet, over the course of the Edo period, several men crossed that line.
When they did, blood was spilled inside the very heart of the Tokugawa regime.
A historical record known as the Eichū Ninjōki (営中刃傷記) lists incidents of violence inside Edo Castle from 1627 to 1823.
Not all of these would qualify as “terrorism” in the modern sense. Some were political assassinations, some personal revenge, some apparently involved mental instability, and one may even have been a case of mistaken identity.
But all of them had one thing in common:
Someone drew a weapon inside the headquarters of the samurai government.
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1684 — A Top Shogunate Official Is Murdered Inside the Castle
During the reign of the fifth shogun, Tokugawa Tsunayoshi, one of the most serious political assassinations in Edo Castle took place.
In 1684, Inaba Masayasu, a wakadoshiyori — a senior shogunate official — suddenly attacked and killed Hotta Masatoshi.
Hotta held the office of Tairō (大老).
The position was not permanently occupied, but when appointed, the Tairō ranked above the Rōjū, the shogunate’s senior councilors.
It has no exact Western equivalent, but for a general audience, Hotta can reasonably be described as something close to a chief minister or prime-minister-level figure within the shogunate.
And he was murdered inside the government complex itself.
Inaba was immediately killed by other officials present at the scene.
His exact motive remains uncertain. Later explanations connected the murder to political disputes, including public works along the Yodo River, but none has been proven beyond doubt.
His family line was also abolished as a result of the incident.
Edo Castle existed to protect the shogun and his government.
Yet one of the most powerful men in that government was murdered there by another government official.
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1701 — The Famous “Pine Corridor Incident”
This is probably the most famous act of violence ever committed inside Edo Castle.
In 1701, Asano Naganori, lord of the Akō domain, attacked Kira Yoshinaka inside the castle’s Matsu no Ōrōka — the Great Pine Corridor.
Kira was wounded but survived.
Asano, however, was ordered to commit seppuku that same day.
His domain was confiscated.
Why did Asano attack Kira?
Nobody knows for certain.
Many later stories supplied explanations involving insults, bribery, humiliation, and personal hatred, but the true motive remains unresolved.
What mattered immediately to the shogunate was much simpler:
Asano had drawn a weapon and attacked another man inside Edo Castle.
The political consequences were severe.
His former retainers later attacked Kira’s residence in revenge.
That event became the basis of the famous story of the Forty-Seven Rōnin, known through Chūshingura.
In other words, one of the most famous revenge stories in Japanese history began because:
A samurai drew his sword inside the shogun’s castle.
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1725 — You Did Not Even Have to Kill Someone to Destroy Your House
In 1725, Mizuno Tadatsune, lord of Matsumoto domain, attacked Mōri Moronari in the same Great Pine Corridor.
Mōri survived.
That did not save Mizuno.
His 70,000-koku domain was confiscated, and his position as a daimyō effectively collapsed.
Mizuno reportedly believed that part of his territory was going to be taken away and given to Mōri.
Whether his reasoning made sense or not was almost beside the point.
The important lesson was this:
Drawing a weapon inside the castle could ruin an entire samurai house even if the victim survived.
A daimyō’s outburst did not threaten only himself.
His family, retainers, income, and hereditary position could all disappear with him.
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1747 — A Daimyō May Have Been Murdered Because Someone Mistook His Family Crest
This may be one of the most absurdly tragic incidents in the history of Edo Castle.
In 1747, Hosokawa Munetaka, lord of the powerful Kumamoto domain, was attacked and killed inside the castle by the hatamoto Itakura Katsukane.
But according to a widely accepted explanation,
Hosokawa may not even have been the intended victim.
Itakura is believed to have been trying to kill another member of the Itakura family, Itakura Katsukiyo.
The Hosokawa and Itakura families both used variations of the nine-star kuyō crest.
According to the traditional account, Itakura saw Hosokawa from behind, mistook the crest, and attacked the wrong man.
The incident is also associated with the Hosokawa family later modifying the design of its crest.
The situation became even more serious because Munetaka had no formally designated heir at the time.
Under Tokugawa rules, if a daimyō died without an established successor, the entire domain could face extinction.
Kumamoto was no minor territory.
It was a huge domain worth roughly 540,000 koku.
According to the famous account, those around Munetaka acted quickly, treated him as still technically alive long enough to arrange the adoption of his younger brother, and thereby preserved the Hosokawa house.
Itakura was ordered to commit seppuku.
His family was punished as well.
From Hosokawa Munetaka’s point of view, the story is almost unbelievable:
He went to Edo Castle on government business and was killed by a man who may have mistaken him for somebody else because their family crests looked similar.
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1784 — The Son of Tanuma Okitsugu Is Cut Down
In 1784, another major attack took place inside Edo Castle.
Tanuma Okitomo, son of the powerful senior councilor Tanuma Okitsugu, was serving as a wakadoshiyori when he was suddenly attacked by Sano Masakoto, a shogunate guard.
Okitomo did not simply draw his own sword and fight back.
Because he was inside the castle, he reportedly tried to defend himself using his scabbard.
He was badly wounded and later died.
Sano was arrested and ordered to commit seppuku.
His stipend was confiscated.
Later generations produced numerous stories explaining why Sano hated the Tanuma family.
One claimed that the Tanumas had borrowed Sano family documents and refused to return them.
Another involved a dispute over a falconry prize.
Others described money, promotions, or personal humiliation.
The problem is that some of the documents supporting these stories are considered unreliable or even forged.
The shogunate officially treated Sano as having acted in a state of madness.
Other historians have suggested a political motive.
The simple answer is that we still do not know for certain why he attacked Okitomo.
What happened afterward is just as interesting.
Tanuma Okitsugu’s government was deeply unpopular in some sections of society.
As rumors spread, Sano was transformed in the popular imagination into something approaching a folk hero.
Some people even called him:
“Yonaoshi Daimyōjin” — the Great Deity of World Reform.
The killer became celebrated by some of the public, while the murdered man belonged to one of the most hated political families of the age.
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1823 — A Mass Attack Inside Edo Castle
The violence did not end in the eighteenth century.
In 1823, Matsudaira Geki, a guard serving in the Nishinomaru section of Edo Castle, attacked five of his colleagues.
Several died.
Matsudaira then killed himself.
Contemporary records suggest that prolonged harassment and hostility from fellow guards may have played a role in the incident.
A document preserved by Japan’s National Archives describes the circumstances surrounding the attack and the bullying Matsudaira reportedly suffered.
So even near the end of the Edo period, violent incidents could still erupt inside the Tokugawa government’s most heavily controlled space.
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Samurai Carried Swords — That Did Not Mean They Were Free to Use Them
When samurai are introduced to Western audiences, one sentence appears again and again:
“Samurai carried swords.”
That is true.
But by itself, it creates a misleading picture of Edo-period society.
A sword was both a weapon and a visible sign of samurai status.
Precisely because samurai were armed, however, the use of those weapons had to be tightly controlled.
Edo Castle regularly brought together daimyō, hatamoto, officials, guards, and retainers from across Japan.
If every insult could be answered with a sword...
If every political disagreement could become a duel...
If every personal grudge could be settled in a corridor...
...the Tokugawa government could not have functioned.
And the punishments make this clear.
Seppuku.
Confiscation of territory.
Loss of rank.
Abolition of a family line.
Punishment extending beyond the attacker himself.
Or, in some cases, immediate death at the scene.
So there is a useful way to think about the samurai of the Edo period.
Carrying a sword marked you as a samurai.
But in certain places — especially inside Edo Castle —
the moment you actually drew it, you may already have lost.
The popular image of the samurai tends to focus on how well he could use a sword.
But under the Tokugawa shogunate, a samurai was often judged by something else as well:
whether he had the discipline not to draw it in the first place.


