Photo/Illutration Toshiya Nakata takes a close look at a replica sword at the Gifu University in Gifu on March 22. (Fumiko Takaki)

GIFU—Toshiya Nakata set himself the task of unlocking the secrets behind the strength of Japanese swords after he became fascinated with their beauty a few years ago.

“Japanese swords, made from iron, fall into decay unless they are properly cared for,” said Nakata, a researcher specializing in strength and fracture of materials. “Still, blades forged during the Heian Period (794-1185) have been carefully maintained over the centuries and remain in good condition to this day.”

Nakata, 41, has raised 2.3 million yen ($18,000) through crowdfunding to fathom now-lost techniques that produced swords of excellent craftsmanship, such as those fashioned by the master swordsmith Masamune during the Kamakura Period (1185-1333).

After receiving doctorate from the Muroran Institute of Technology’s graduate school, Nakata mainly studied strength of metal auto parts at Kobe Steel Ltd.’s research institute and Okayama University.

It was only after he became an associate professor at Gifu University’s Faculty of Education that he took an interest in the historical background and artistic value of Japanese swords, and that was in winter 2019.

Nakata wanted his would-be teacher students to learn about traditional businesses in Gifu Prefecture, such as cutlery.

The city of Seki in the prefecture is known as a center of cutlery production. One of the prefecture’s most celebrated sons is Seki no Magoroku, a master swordsmith in the Muromachi Period (1336-1573).

Nakata started by visiting the Sano Art Museum in Mishima, Shizuoka Prefecture, known for its collection of Japanese swords.

At a monthly event to observe noted swords, many of them designated as cultural properties, he and other participants bowed in reverence and straightened up before picking them up.

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A sample measuring 15 millimeters or so is used for analyzing strength of swords, compared with a large one for ordinary metal products. (Fumiko Takaki)

Nakata also started analyzing strength of Japanese swords using samples of unused blade material provided by a swordsmith.

Steel takes on different characteristics depending on levels of heat and shaping techniques during the manufacturing process.

According to Nakata, Japanese swords use hard high-carbon steel on the outside to improve sharpness and steel with a lower carbon content on the inside to absorb the impact of a strike.

The dual structure allows Japanese blades to retain their sharpness while they are not easily broken or bent.

“Adjustments are made by millimeters to control the hardness of a sword,” Nakata said. “No modern metal products are based on so complex a structure.”

But the elaborate structure proved to be a challenge for analysis. Tiny samples measuring 15 mm or so are required for analyzing strength of swords, while specimens as long as a pen are used for ordinary metal products.

It is difficult to secure funds for such basic research, compared with practical studies on automobiles.

Nakata has resorted to crowdfunding, hoping to cash in on a recent sword boom fueled by the “Touken Ranbu” video game franchise and “Demon Slayer: Kimetsu no Yaiba” manga series.

“Japanese swords have attracted many fans with their charms as works of art and cultural properties,” Nakata said. “I hope they will take interest in our research on their strength, too.”

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