Muramasa Katana: The Terrifying Legends of the Demonic Sword

Discover the demonic Japanese weapon known as the Muramasa Katana. Learn its history and debunk the myths.

Jun 7, 2023By David Mickov, BA History, BA Philosophy

muramasa katana


Japan is well-known for having the world’s most famous sword, the Katana. However, there is one Katana blade that is shrouded in mystery, with terrifying legends surrounding its name: the Muramasa Katana. This article will discuss the most famous of these legends as recorded in Negishi Shizue’s Mimibukiro. You will learn how the sword made Samurai lose their minds, brought bad luck, and even caused the collapse of the Shogunate. Then we will debunk the myths and take a look at the facts.


Muramasa: The Madman Swordsmith 

katsushika hokusai the swordsmith
The forging of a Katana sword, 1802, via Metropolitan Museum of Art


The man who created the Muramasa went by the name of Sengo Muramasa. It is said that Muramasa lived through a series of misfortunes that made him lead a sort of bizarre life. He would be angry, arrogant, jealous of everything around him, and had ambitions that were purely evil.


Eventually, he was shunned by everyone, further raising his negativity and aggressiveness. At times, his mind swayed over the edge, leading him into madness. Like many Japanese ghost stories, he quickly became bloodthirsty and sought vengeance for the life that did him wrong. Muramasa visited fields where big battles occurred and obtained all sorts of metal and remains of Katana swords. Negishi Shizue, the author of Mimibukiro, where most of these legends come from, says that Muramasa would go to dark and empty locations, often surrounded by sad backgrounds, like ghosts or suicides. There, he would start creating the legendary Muramasa Katana imbued with his demonic spirit. He would construct the blade for days, months, and years until it was finally made.


It was said that the Muramasa had the sharpest blade of all the other Katana. Its beauty struck everyone who wished to wield it for themselves. This would lead to its quick recognition and dispersion throughout the whole of the army. However, stories of users losing their minds would quickly overturn its success in battle.

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yata goroemon suketake
A frenzied samurai, Yata Goroemon Suketake, 1847 via National Gallery of Victoria, Melbourne


It is said that whoever wields the Muramasa Katana becomes bloodthirsty. Samurai users of this sword eagerly awaited the next battle or just a reason to kill someone. The Muramasa was thirsty for blood at all times. Sometimes it would be satisfied with a normal life, but at times it sought the life of a higher noble. If it remained sheathed for a long time, it could sway the user’s mind to do unthinkable things without even remembering them.


No matter what was the case, once the Muramasa was unsheathed, it needed to be satisfied with the taste of blood. This meant that if the samurai wielding it couldn’t kill someone, they would end up killing themselves to satisfy this demonic sword.


Because people were frightened by this terrifying bloodlust, they were destroying the swords or sometimes just removing the engraved name of Muramasa from the blade. However, apparently just removing the name wasn’t enough, as there are stories of merchants selling this sword and getting the urge to kill those around them.


Mysterious Charm

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Samurai with a drawn Katana sword, via MetMuseum


As Negishi Shizue wrote, the Muramasa had a mysterious charm and energy that people. Its beauty struck even those who were against war and the use of Japanese weaponry. The Muramasa has a very sharp edge that, when looked at closely, one might notice that it has two eyes on the sides at the blade’s end. This charm would entice people to obtain the sword.


Frenzied Samurais

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Bloodied and frenzied Samurai in an uprising, via National Gallery of Victoria, Melbourne


There are many tales surrounding the use of the Muramasa by samurai warriors. Some are said to have even killed close family members without remembering it. There is a story of a samurai who knowingly bought a Muramasa, even though it had been forbidden to use. The samurai had decided that he would erase the engraving under the handle. However, one day, after having used this Muramasa in training, he came home to his loving wife, placed the sword in the same room, and slept. At some point in the middle of the night, he woke up, looked down, and saw that his clothes were red. He was standing in a pool of blood, having killed his wife to satisfy the Muramasa without even knowing.


In another story, a samurai by the name of Matsudaira Geki forgot his bushido and killed his best friend from childhood after going into a Muramasa-driven frenzy. He then used the sword to kill himself.


Muramasa vs. Masamune

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The Muramasa sword could make anyone lose their mind, via the Philadelphia Museum of Art


Masamune is the most renowned Japanese swordsmith. More or less, he came from the same period as Sango Muramasa. They were both extremely good Katana makers and in some stories, they appear competing against each other to find the best sword. According to one such story, one day, Masamune and Muramasa were testing their swords’ sharpness and durability. However, as both did exceptionally well, they decided to place their swords inside a fast-moving river to test them better. When inside the river, with the blade tip pointing against the current, the swords cut dead leaves swiftly in halves without a problem. But when fish or other types of debris passed by, the Muramasa katana was the only one that killed.


This tale indicates that the Muramasa will kill even those who are peaceful and living. As it is said in the Japanese 落穂集 or Collected Ears in English — a series of early 18th-century folklore texts — this was the reason why the shogun Ieyasu ordered the sword’s destruction.


Modern Sharpness Test

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Sano Jirōzaemon Murdering a Courtesan, 1886, via Philadelphia Museum of Art


There was a researcher by the name of Kotaro Honda who had made a very good machine for testing and studying all types of metals. The word got around fast, and people from all over the world were bringing in their metal heirlooms for testing.


Kotaro’s machine had never failed even once. But one day, while testing an ancient and authentic Muramasa sword, something went terribly wrong. First of all, while in possession of the Muramasa, his heart would not stop pounding fast. Then while he tested the metal’s sharpness, the machine would go crazy and numbers would jump up and down on the scale. He then decided that this type of metal could not be scanned and that something was wrong with it.


Deaths Inside the Shogunate Family

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Ieyasu of the Tokugawa dynasty, via Tokugawa Art Museum


In the Kokiki and the Matsudaira Chronicle, there are multiple legends and stories regarding how the Muramasa katana was the sole destroyer and biggest enemy of the Tokugawa family.


It is said that because of the Muramasa’s exquisite sharpness, the shogunate took a liking to and adopted the weapon as its primary sword. However, this was meant to bring unhappiness to the shogun’s family. As it is said in the Mikawa Gofudoki and Mikawa Monogatari — two history books with 45 volumes about the founding days of the Tokugawa — the Muramasa was used to end the lives of the father, the grandfather, the son and the heir of Tokugawa Ieyasu. The very first two were ‘hacked’ from the shoulder down to the waist, and the heir was expected to use the sword to execute himself.


The Truth about the Muramasa Katana

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The Muramasa engraving on the blade under the handle, via The Trustees of the British Museum


The Muramasa Katana is a real and genuine sword that existed in history. However, due to its association with a number of dark myths and stories, it is often referred to as the “evil and cursed Japanese sword.” Also, some people have referred to it as the most powerful Katana ever made, even though it is not true, probably due to its legendary status. In reality, it is just as powerful as a regular Katana but much sharper, which could have easily resulted in self-injury. Also, this razor sharpness leads to its durability being way weaker and its life span much shorter.


The Real Muramasa Swordsmith

tsukioka yoshitoshi tokugawa fifteen generations
The Tokugawa Dynasty, via Honolulu Museum


A renowned swordsmith, Sengo Muramasa is also the subject of a great deal of conjecture and speculation due to the lack of information available about his life. Nobody is entirely sure of his exact date of birth. Everything we know about him is intertwined with legend, so it is difficult to tell the real from the fictitious.


During the time of feudal Japan, Muramasa was one of the best and most famous swordsmiths. During the Muromachi era, which lasted from the 14th to the 15th century (1336-1537 CE), he spent his whole life trying to achieve a better level of sword-forging. He was successful in establishing his own school, which quickly gained a reputation for the superior craftsmanship and razor-like edge of its blades. As a result, his works became a treasure that was much sought by elite members of the classes such as commanders and samurai of the Tokugawa dynasty.


Although a legendary and talented swordsmith, he didn’t really come close to his rival and competitor in the Katana-making world, Masamune, who is acclaimed to be Japan’s greatest swordsmith.


Debunking the Legends


Because of its razor-like edge, the Mikawa (sometimes known as the Tokugawa dynasty, which ruled Japan for 300 years) preferred the Muramasa sword. So whatever unfavorable occurrence occurred to them is attributed to the Muramasa sword because they actually used and employed the Muramasa sword.


Samurai from Kuwana to Owari were known to frequently use the Muramasa sword under the Tokugawa. Ieyasu (1603-1605 or 1615) is said to have banned the Muramasa’s use around the time when his father and grandparents were murdered by these samurai, which is where the stories around them originate. This tale, on the other hand, is very certainly a fabrication due to the fact that Muramasa is in fact a legacy of their lineage and heirloom.


Even if Ieyasu’s ban was real, there is evidence that the Muramasa was actually still in use under the Tokugawa. It is known that Ieyasu stopped accepting gifts that were signed with the Muramasa signature, and the people near him weren’t allowed to use it. Still, soldiers and people in his land were allowed to use it with little to no inspection.


The dark legends started appearing from this possible fear that Ieyasu of the Tokugawa dynasty might have had of this sword when the fight against the Tokugawa Shogunate started.


Weapon Against the Shogunate

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The Boshin wars or known as the Japanese Civil War, via Honolulu Museum


According to the legends, the Muramasa sword had the power to kill members of the Tokugawa family. That is why during the civil war of the Bakamutso Period, which spanned 1853 to 1868, the final age of the Tokugawa, the anti-imperialists tended to use the Muramasa against them.


That is why the Shishi, or the fighters against the Tokugawa, used the Muramasa as their symbol against shogunate oppression. Even its leaders, Prince Taruhito and Takamori, used the Muramasa when they finally put the Tokugawa, or Edo, period at its end. Even though these legends began earlier with Mikawago Fudoki, written by an unknown writer, it is in this period and during this fight against the Tokugawa that the old stories became what they are today.


There are many legendary swords, but the Muramasa is one of the most popular. It is perhaps the most well-known Japanese sword and has a reputation for being malevolent and demonic.

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By David MickovBA History, BA PhilosophyDavid's passion lies squarely in history. In addition to his bachelor's degree obtained from his hometown - Skopje, North Macedonia, he also has a number of certificates and fieldwork experience in archaeology. If something occurred in the past, David would undoubtedly want to discuss and investigate it more. Because of this, he didn't feel satisfied with merely reading and books, so he went all over the world and passed many lands from Alaska to Florida and Ireland to Turkey. He is both a historical LARP re-enactor and a very huge sword aficionado.