The Greatest Sword Ever Made Was Passed Down for Centuries—then Vanished Into Thin Air 29%
By Darren Orf35%
7/10/2026, 12:00:00 PM
BS Summary: This article contains 26 faulty reasoning types, including Biased Writer Voice, Appeal to Authority, and Post Hoc (False Cause), with Halo Effect as the most egregious example at 20.2% saturation with 167 hits. Analysis detected 1,476 faulty-reasoning hits from 826 analyzed words, generating a BS Score of 39% and a BS Rank of 29% (15,744 of 21,887 articles). This article is better (less manipulative) than 71.90% of the article peer group.
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Of the thousands of incredible swordsmiths throughout Japanese history, none compare to Gorō Nyūdō Masamune, who created some of the country’s most lasting treasures.
One of those treasures is the Hōnjo Masamune, a sword wielded by some of Japan’s most famous historical figures, including Tokugawa Ieyasu—the founder of the Tokugawa Shogunate.
Despite being declared a national treasure in 1939, the sword vanished during Japan’s surrender to Allied Forces at the end of World War II.
Japan is renowned for many things, but few nations rival its legacy of sword-making.
That lineage of steel-based perfection owes much to one 13 th -century swordsmith: Gorō Nyūdō Masamune.
Masamune—who lived from 1264 until 1343 C.E., a period when samurai warriors steadily gained power throughout the island nation—is regarded by many historians as perhaps the greatest swordsmith in Japanese history.
His most famous innovation is his mastery of nie —large, visible martensite crystals that create striking visual effects in the steel.
The effects is achieved through differential hardening, a process through which the spine of the sword is coated in thick clay so it cools more slowly than the edge during quenching.
This leaves the edge hard and sharp while keeping the spine flexible and resilient.
Masamune’s magnum opus is widely considered to be a sword known as the Hōnjo Masamune.
Masamune swords that survive to this day typically have two names—the name of a clan or important historical figure who owned the sword, and the name of the swordsmith himself.
Although Masamune forged the weapon around the turn of the 14 th century, it would only become known as the Hōnjo Masamune centuries later when famous general Hōnjo Shigenaga wielded the weapon in service to the Uesugi clan.
The story goes that during the fourth Battle of Kawanakajima, the Masamune-forged weapon sliced Shigenaga’s helmet in half, but the famous general survived the encounter and claimed the sword as his own.
While the sword was prized by Shigenaga for years afterward, he eventually sold it in 1595 to the Toyotomi clan, who ruled Japan at the time.
With the clan’s dissolution in 1615 and the rise of the Tokugawa Ieyasu—arguably one of the most important figures in Japan’s history—the sword became a hereditary symbol of power during the Tokugawa Shogunate.
Despite the clan’s downfall in the late 19 th century, the family held on to the sword, and the weapon was officially declared a national treasure in 1939.
But its centuries-long journey would finally reach its most perplexing chapter at the tail end of World War II .
On August 15, 1945, Japan unconditionally surrendered to Allied forces, officially ending the deadliest war in human history.
As part of the terms of that surrender, Japan was required to relinquish all of its weapons, including samurai swords.
Accordingly, Tokugawa Iemasa—a descendent of Ieyasu—surrendered the Hōnjo Masamune at Mejiro police station in Tokyo in December of 1945.
Tokugawa Iemasa hoped to set an example of cooperation with the Allied Occupation for his fellow citizens, but after surrendering the blade, it was never seen again.
The story gets stranger.
On January 18, the Mejiro police said that a man named “ Sgt.
Coldy Bimore ” collected the swords for the Foreign Liquidations Commission, but no one assigned to collect Japanese weapons went by that name.
The Allied forces started melting swords (or even throwing some into the sea), but General Douglas MacArthur halted the destruction of swords later that year after learning that many of them were simply family heirlooms.
To this day, no one knows where the Hōnjo Masamune might be.
There are vague, unsubstantiated theories, but no concrete proof.
However, not all hope is lost.
In 2013, a private collector brought a sword to the Kyoto National Museum that was confirmed to be the lost Shimazu Masamune, a creation of the same legendary swordsmith who created the much-treasured Hōnjo Masamune.
If one of Masamune’s sword could re-emerge after so long, may be the Hōnjo Masamune can as well.
The legendary sword might remain missing for now, but the search continues.
Darren lives in Portland, has a cat, and writes/edits about sci-fi and how our world works.
You can find his previous stuff at Gizmodo and Paste if you look hard enough.
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