How the Evolution of Sharpness Shaped the Japanese Spirit and Food Culture
Why do Japanese blades captivate the world? The answer is only half contained in the skill of the blacksmith. The other half—perhaps an even greater share—has been carried by the existence of the whetstone.
This article is based on a profound historical lecture of over one hour delivered by Masashi Fujiwara, Representative Director of the Japan Knife Sharpening Association. Using nine major transitions as its framework, we will explore how humanity learned to face “stone,” and how that journey ultimately led to the ability to design the “taste” of ingredients. We will delve into the full scope of that evolution in depth.
Introduction: The Starting Point of Sharpness Is the Whetstone
“When talking about knives, I believe we must start by talking about whetstones first.”
Fujiwara opens with this statement. Of course, steel and blade geometry matter, but in the end it is the whetstone that breathes life into the edge—transforming it into “sharpness.”
Why did the Japanese develop such an intense devotion to sharpness, and build a culture unlike any other? The answer is simple: Japan is one of the world’s rare true treasure houses of whetstone geology. From the Stone Age to the present—and into the future—this is where the grand story begins.
1. The Polished Stone Tool Era: The Beginning of Human “Control”
In human history, the evolution of tools accelerated dramatically at the moment we shifted from “striking” to “grinding.”
Chipped stone tools were made by breaking stone—tools influenced heavily by chance. But with the arrival of polished stone tools, people learned to rub stone against stone and shape materials into the “intended form” they envisioned.
Fujiwara defines this as the beginning of sharpening.
Archaeological sites have yielded stones bearing clearly intentional grinding marks. Making a tool sharper, or refining it for use—this act of grinding stone with purpose became the very first step of Japan’s sharpening culture, a tradition that would continue for over 10,000 years.
2. The Yayoi Period: Stone Gains “Value” and Begins to Circulate
In the Yayoi period, whetstones rose from being mere stones at hand into valuable “exchange resources.”
Archaeological findings reveal that certain ruins contain whetstones that could not possibly exist in the surrounding geology. This is evidence that whetstones were transported across distances—from regions that produced superior stone to regions that did not.
“Stone from that area cuts well.”
Such knowledge was already shared among people, and whetstones were bartered for food and other valuables. Fujiwara sees here the emergence of whetstone specialists—people who could discern subtle differences in stone, identify quality, and treat it as a tradable good. The Japanese “aesthetic eye” for stone began sharpening itself from this era onward.
3. The Heian Period: Quality Rankings and the Birth of “Iyo-To”
By the Heian period, whetstones transcended their role as simple tools and began to carry names as “brands.”
A representative example is Iyo-to, produced in what is now Ehime Prefecture. When a stone carries a place name, it means its quality has been widely recognized and that it holds public value—market value.
In this era, whetstones evolved from “pebbles” into “stone,” and from “stone” into “products with quality.” As demand for metalworking increased—whether for swords or agricultural tools—the choice of whetstone became a crucial factor that determined the outcome of a craftsman’s work.
4. The Kamakura Period: The “Revolution” of Discovering Natural Finishing Stones
Among all turning points in Japanese blade history, the Kamakura period stands as the most intense and most important. In Kyoto, natural finishing stones (awasedo) were discovered.
The “Miracle” Born from Kyoto’s Geology
Kyoto’s finishing stones come from geological layers that are extraordinarily rare on a global scale. Fujiwara calls this “Japan’s miracle.”
With finishing stones, blades evolved beyond being “tools that simply cut.” They became objects that cut with terrifying power—and shine with beauty: works of art.
Sharpness as a Military Secret
Finishing stones were at the core of military industry. Japanese swords sharpened to the extreme granted overwhelming battlefield advantage. For this reason, whetstone mountains were strictly controlled by those in power.
The golden age of the Japanese sword—symbolized by master smiths such as Masamune—also coincides with the era of these stones. “Because the stone existed, blacksmiths could draw out their full potential.” It was a fortunate age when the evolution of tools expanded the limits of human technique.
5. The Edo Period: The Aesthetics of the Japanese Kitchen Knife, Nurtured by Peace
When warfare ended and society stabilized in the Edo period, the main arena of whetstones shifted from the battlefield to the kitchen.
Deepening Food Culture and the “Pull-Cut”
Stability dramatically elevated food culture. The forms of knives used by modern professionals—yanagiba, usuba, and deba—were established in this era.
Cookbooks began to include instructions such as: “Slice sashimi by pulling; do not move the blade back and forth.” This technique is only possible when the edge has been refined to extreme thinness and sharpness through finishing stones.
The Spirit of “Mottainai” and Care
With limited resources, the Japanese cultivated the spirit of mottainai—the belief that wasting is shameful. Tools were cherished, resharpened, and kept alive as long as possible.
This maintenance culture—the culture of care—became a symbol of Japanese diligence and sensitivity. Fujiwara emphasizes that it was the Edo period that formed the spiritual foundation of sharpening culture that continues into the present.
6. Meiji to Early Showa: The Peak Era of Natural Stone Mining
From the Meiji era through the early Showa period, natural whetstone mining reached its peak.
As mechanization advanced, mountains were excavated on a large scale using heavy machinery and dynamite. As a result, high-grade natural whetstones—once accessible only to elites—spread broadly through the world of craftsmen.
Kyoto’s whetstone mountains became especially vibrant, and the market was filled with stones of extraordinary variety.
7. Early Showa: The Emergence of Synthetic Stones and the Birth of “Standards”
In the 1890s, abrasives such as silicon carbide were invented in the United States, and the wave of synthetic whetstones reached Japan.
At first, synthetic stones were said to be inferior to natural ones. But they possessed a decisive advantage: standardization through grit numbers.
Natural whetstones belonged to a sensory world—“this stone feels a bit harder.” But synthetic stones could guarantee quality in numbers: “1000 grit,” “6000 grit.” This uniformity and stability was explosively accepted in an industrializing Japan. Even without connoisseurs, anyone could sharpen under the same conditions. It was, in effect, the democratization of sharpening.
8. Late Showa to Heisei: The Completion of Synthetic Finishing Stones and a Reversal
Around 40 to 50 years ago, synthetic whetstone technology finally reached a precision in the “finishing” domain comparable to natural stones. This triggered a kind of reversal within the knife industry.
Why Aogami (Blue Steel) Became “Truly Sharp”
In the past, hard steels such as Aogami were believed difficult to fully exploit because natural stones lacked sufficient cutting power. However, the emergence of high-performance synthetic finishing stones made it possible to sharpen even very hard steels with precision and extreme keenness.
Fujiwara’s insight—“Older literature often says Shirogami (White steel) is better, but that was because the stones of that time could not catch up to Aogami”—suggests that whetstone evolution even reshaped how steels themselves were evaluated.
9. Recent Years: Diamond Plates and the Revolution of Flattening
In the modern era, what Fujiwara values most is flattening (mennaoshi) using diamond plates.
A Shift in the Preconditions of Sharpening
A whetstone inevitably dishes in the center as it is used. Sharpening on a dished stone distorts the angle, and sharpness becomes unstable.
“If your ruler is bent, you can’t draw a straight line.”
Diamond plates enforce this simple truth. By flattening the whetstone surface with diamond—a material that does not deform—today’s sharpeners have gained an environment in which they can create edges more precise than anyone in history.
Detailed Report: Designing the “Taste” of Ingredients with Whetstones
After this long history, where do we stand today?
Fujiwara shares a remarkable conclusion through his own “squid slicing comparison experiment.”
The Taste of Natural Stones
Natural stone particles fracture during sharpening, giving the edge microscopic rounding. When cutting squid, the cells are sliced while being slightly “crushed,” allowing internal compounds to seep out—bringing out a sticky sweetness more strongly.
The Taste of 30,000-Grit Synthetic Stones
An edge refined to the limit with synthetic stones cuts cells cleanly without damage. The cut surface becomes mirror-smooth, and the fresh, crisp texture—the vivid crunch felt the instant it touches the tongue—stands out.
It is not a matter of “which is better,” but rather: “Which taste do you want to deliver to the guest?”
Modern sharpening has moved beyond simple edge-making, reaching the domain of tuning—the act of determining the very taste of cuisine.
Conclusion: By 2030, Sharpening Will Become the “Analog Counterattack”
We are approaching an era in which AI and robots may cook meals. Yet Fujiwara finds in this a place where only humans can shine.
“If you only want efficiency, machines are enough. But being able to explain why you chose this stone, and why you aimed for this taste—with story and logic—that will become the value of chefs and sharpeners in the coming era.”
The act of rubbing stone, which began in the Stone Age 10,000 years ago, has evolved into one of the most luxurious and creative forms of entertainment.
The next time we hold a whetstone, we are holding 10,000 years of history in our hands.
To draw out the true nature of ingredients—beyond mere sharpness—
we continue to polish our knives today.
Source: Japan Cutlery Research Institute YouTube Channel
“[Complete Edition] The History of Japanese Whetstones”
Commentary: Masashi Fujiwara (Representative Director, Japan Knife Sharpening Association)
Interviewer: Tomohiro Kakinuma (Representative, KAKINUMA)