As we have seen, natto is not unique to Japan; it is found in other parts of Asia as well.
Let's explore that in greater detail.

The natto in Japan is made by fermenting soybeans with the natto bacillus, a type of Bacillus subtilis known as Bacillus subtilis (natto). In modern-day Japan, natto is almost always made using pure cultured natto bacillus, and so the result is natto that is uncontaminated by other bacteria and has firm fine threads.

In contrast, not all natto in other parts of Asia creates fine threads when stretched. In fact, even if it has the familiar natto fragrance, most natto in other parts of Asia does not create fine threads.

This is because the Bacillus subtilis that is used for fermentation is not necessarily Bacillus subtilis (natto).

With the exception of the Korean cheonggukjang, natto in other parts of Asia is fermented using Bacillus subtilis derived from leaves such as fern, banana and fig. As the many varieties of Bacillus subtilis differ depending on the type of plant, in general a different type of leaf is used by each ethnic group, and each group has its own favorite variety of Bacillus subtilis.

Incidentally, as in the case of Japanese natto, cheonggukjang is made using pure cultured natto bacillus.

What is unique about natto as compared to other fermented foods throughout the world?
The most unique thing about natto is its viscosity. There may be no other fermented foods that develop thin threads when stretched as does natto. Cheese is a food that also stretches, but the way it stretches is different from the fine threads of natto.
These threads are rich in components that can enhance both beauty and health. and they can be called the symbol of natto.

Another quality that makes natto somewhat different from other fermented foods is the fact that natto is ready in a short period of time.
In general, fermented foods are foods that have longer shelf life thanks to the microorganisms that accomplish the fermentation. In almost all cases, a long period of time is required before they are ready to eat. Factoring in the aging time needed following fermentation, it is not unusual for them to take several years before they are finished, as in the case of cheese and wine.
By contrast, natto is surprisingly speedy. Fermentation takes only one full day.
Even if the natto is aged, it is ready in a few days. And yet the principal ingredient, dried soybeans, can be stored for several years.

So natto is made from an ingredient that can be stored for a long period of time, and it can be fermented in a short period of time. This combination gives natto tremendous reserves of fermentation power.

Bread, wine, beer, cheese... countless fermented foods are served on dining tables around the world. Many fermented foods are invented in various places and spread throughout the world, enriching our culinary lives. Traditional fermented food cultures unique to specific locations have been nurtured in keeping with the climate, natural features and ecosystem of various locations, as well as in accordance with the properties of the fermenting microorganisms in those locations.
For example, in Europe, a location with a dry climate and sparse rainfall, there tend to be fewer fermented foods that use mold as compared to Asia. Mold prefers a humid environment.

Throughout the world, there are products that few would suspect as including fermentation in their manufacturing process, such as chocolate, and there are other fermented foods that have a powerful aroma and overwhelming visual appearance. One wonders: how does natto appear in the eyes of the rest of the world?

The world of fermented foods is not one that becomes deeper and deeper as you learn more and more. Rather, it is immediately evident that this world has both depth and breadth.
It is amazing to consider that a macro world on a global scale has been created by the micro-world of microorganisms.

The culture of making dairy products from the milk of domestic livestock such as cows and goats is said to have originated with nomads who traveled together with their livestock. A popular folktale in the Middle East tells the story of an Arab merchant who poured goat's milk into a water bottle made from a sheep's stomach. At some point during the journey, the milk separated into liquid and a white lump — in other words, cheese. The method of making cheese actually did come to Europe from the Middle East.
"The Basics of Fermentation" (Seibundo Shinkosha Publishing Co., Ltd.)

Cheese is one of the world's most popular fermented foods. There are said to be more than 1,000 varieties of cheese. Despite this diversity, all of these varieties use the same principle to make cheese from milk. The milk is sterilized by heating, and then lactic acid and yeast are added. After the milk has separated into liquid and solid parts, the solid part is fermented, again using lactic acid.

As in the case of natto, the lactic acid that is used for fermentation is a type of bacillus. In some cases, mold is also used, in order to produce cheese with umami and depth. Blue cheese and Camembert cheese are examples of cheese in which mold is also used.

Like cheese, yogurt is a dairy product that is also fermented with lactic acid. It is a type of fermented milk that is made using all parts of the milk.

The WHO and FAO definitions of yoghurt specify the strains of lactic acid to be used in its creation. Yoghurt is defined as products that are produced through fermentation resulting from the presence of large quantities of Lactobacillus bulgaricus and Streptococcus thermophilus.

Sauerkraut, a traditional German fermented food, is made by pickling strips of cabbage in brine to achieve lactic acid fermentation. Would describing it as sour pickled cabbage enable one to imagine what it tastes like? It is a fermented food with a long history: records show that it was already being eaten in the days of ancient Rome.

Sauerkraut is fermented not by adding lactic acid bacteria but by using the lactic acid bacteria that is already present on the cabbage leaves. Lactic acid bacteria is able to withstand salt content, and salt is also able to suppress other bacteria. It is the lactic acid produced by the lactic acid bacteria that gives sauerkraut its sourness.

Sauerkraut has a mellow flavor and an appealing sourness that results from fermentation. It goes well with fatty meat dishes.

Thua nao is a type of natto produced in the mountainous areas of northern Thailand and in northern Laos. It is eaten by a minority group in Myanmar called the Shan and other ethnic groups, primarily those with roots in southwestern China. In the local language, "thua" means soybean and "nao" indicates a fermented state.

Like natto, the method of preparing thua nao is simple. Washed soybeans are boiled for around eight hours and are then placed on a large leaf like a fig leaf inside a bamboo bag and fermented.

The difference between thua nao and natto is that thua nao is subjected to secondary processing following the completion of fermentation by the Bacillus subtilis on the leaf. The thua nao is pounded while being mixed with salt and spices to form a coarse paste. These days thua nao is seen as something that is bought at the market rather than being made at home — like miso in Japan.

Thua nao paste is fried with ground meat and chili peppers. It is also mixed with rice noodles in soup to create a regional cuisine known as khao soi, which has an outstanding umami flavor.

The paste can also be stretched flat like a rice cracker and dried to form a type of thua nao that can be preserved for a long time. This type of thua nao is versatile and can be fried, deep-fried and so on.

Another member of the unsalted soybean fermented food family is tempeh. Tempeh has a long history — it has been eaten in Indonesia for 400 to 500 years — and so even in Japan its name recognition has been increasing. It is a particularly important source of protein for vegetarians who are looking for a substitute for meat.

Tempeh is fermented using rhizopus, a type of mold that is also known as tempeh fungus. It has long, fluffy white fungal filaments that resemble Camembert cheese. In the past, rhizopus derived from hau tree leaves and other leaves was used. These days, pure cultured tempeh fungus and a mixed fungus called ragi are used as tempeh starter.

Soybeans that have been steeped in vinegar water are rubbed together to remove the skins. Making the beans acidic with the vinegar water suppresses the activity of the natto bacillus and other bacteria. In addition, removing the skins allows the tempeh fungus to reach the interior.

The peeled soybeans are steamed, and when they have cooled to approximately the temperature of the human skin, the tempeh fungus is added and fermentation is promoted. It takes about 24 hours for the tempeh, enclosed in fluffy white fungal filaments, to be ready.

In Indonesia, sliced tempeh that has been deep-fried and lightly salted is popular.

If what is written in ancient texts that have survived is used as the starting point for history, the origins of natto date back to "Tale of Vegetables and Fishes," which was written around the year 1450 (during the Muromachi period in Japan). This is a parody of the Heike Monogatari, which had been written some 200 years earlier. In this version, the combatants are replaced by vegetable foods versus animal foods (meat and fish).

In the tale, the name of the supreme commander leading the vegetable army is Natto Taro Itoshige, and it is clear from the way he is depicted that he is itohiki natto (natto with fine threads). The Tale of Vegetables and Fishes was reworked in the Edo period to create a story to be read aloud to children. This shows the enduring fascination of this tale.

Other theories about the origins of natto are offered in works such as Shinsarugakuki (An Account of the New Monkey Music, or A Record of New Sarugaku), written in the middle of the Heian period, and Oyudono no Ue no Nikki (Daily Records of the Honorable Lady of the Imperial Office of Housekeeping), written in 1477. Here we have focused on The Tale of Vegetables and Fishes which contains a clear reference to natto with fine threads.

The Muromachi period is said to have been a time in which modern culinary culture first appeared. Many of the basic forms and method of eating Japanese cuisine were established in the Muromachi period. Even if one tries to estimate later rather than earlier out of a sense of caution, it is clear that the Japanese had encountered natto by the time of the Muromachi period.
"Natto Past and Present"

In its regular Natto Surveys that are conducted in Japan, the Japan Natto Cooperative Society Federation asked 2,000 adults throughout the country to describe how they ate natto. What do you suppose the number one method was?

In the most recent survey report, published in 2021, by far the most popular method was "on top of rice."

Almost always eat on top of rice: 48.5%
＋
Often eat on top of rice: 16.0%
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Combined total: 64.5%

The popularity of eating natto on rice is evidenced by the fact that even natto lovers who have endless disputes about what to do with natto before eating it are agreed that it should be eaten on rice.

The "mix well" fans versus the "don't mix" fans... the shoyu fans versus the sauce fans... the timing at which to add seasonings... The animated disputes about such topics will surely sound familiar, evoking recognition with the currently popular phrase "aru aru! ("yeah, that's a thing!").

Placing viscous natto that you have mixed vigorously on top of freshly cooked white rice is a moment of pure bliss. Opening your mouth wide, you inhale air through your nose and smell the savory fragrance. You wish you could share that feeling of happiness with everyone in the world.

The history of natto is also the history of the development of Japanese culinary culture. After all, it is soybeans and rice that are the origins of Japan's culinary culture.

Around 3,000 B.C., rice paddy cultivation spread from China through the Korean Peninsula to Kyushu, and during the subsequent 600 years it is thought to have spread to the northern tip of Honshu and to have become firmly established. Soybean cultivation may have spread together with rice-growing culture.

Two thousand and several hundred years ago, the people of the ancient world viewed the energy of the land that produced soybeans, rice and the other members of the "Five Grains" as something mystical. Before their eyes, they saw soybeans and rice that absorbed this mysterious energy grow, and they saw the power of rice create fine threads in the soybeans. It would be only natural for the people of the ancient world to view natto as a food with a strange power and mystery. Although this is ultimately mere speculation, it definitely stirs the imagination.

Great historical figures and natto. This may seem to be an unlikely combination, but the oral traditions involving the birth of natto include some that evoke gratitude and others in which famous people make an appearance.

One legend from the north of Japan holds that, one morning, a person placed boiled soybeans as an offering on the Shinto family shrine. The end of the shimenawa (sacred rope of rice straw) was touching the boiled soybeans, and the person suddenly noticed fine threads stretching from the boiled soybeans. When, mystified by this sight, people grasped these threads and placed the soybeans in their mouths, a faint sweetness spread throughout their mouths, and they rejoiced, considering this to be a gift from the gods. People ate this food reverently and named it "natto," using the characters for "bean" that is an "offering" to the gods, and thereafter they made it repeatedly.

There are also many legends in which the birth of natto involves a battle in which a brave military commander makes an appearance.

Undoubtedly in those days as well there were people who avoided natto because of its smell and fine threads, which are irresistible to natto lovers.
Although this is pure conjecture, the fact that natto was said to have been given the name of a gift from the gods or a famous historical figure would seem to indicate that people wanted to treat it as a good thing. At least the many legends would seem to indicate this desire.

Let's look at another natto origin story, this version involving Prince Shotoku.

In the Asuka period (around the year 600), Prince Shotoku had a Buddhist statue built in the area that is now Koto-cho, Echi-gun, Shiga Prefecture. On his way back, he stopped to rest his beloved horse at a place named Shodo, and gave the horse some boiled soybeans. He created a straw bundle to contain the soybeans that the horse did not eat and hung it on the branch of a tree. The boiled soybeans turned amber-colored and developed fine threads, and they were delicious when salted. The people of the village rejoiced and begged Prince Shotoku to tell them how to make such soybeans. Thereafter, the village continued to make those soybeans, with everyone in the village participating.

Of the legends of the origin of natto in which great historical figures appear, let's look at some featuring the military commander Minamoto no Yoshiie, also known as Hachimantaro Yoshiie, who lived in the latter part of the Heian period. Whether is is because the heroic tales of Yoshiie have a great deal of affinity with the origin of natto, or because the stories contain a kernel of truth, the stories that have been passed down assume certain patterns. According to "Natto Past and Present," there are many stories that involve the Former Nine Years' War (1051) and the Later Three Years' War (1083).

Legend 1
Once when Yoshiie and his troops, together with his father, Yoriyoshi, were deployed near Hiraizumi (Iwate Prefecture), Yoshiie was boiling soybeans to give to his horse when suddenly they were subjected to a night ambush by the enemy. Quickly Yoshiie placed the soybeans in a straw sack and tied it to his horse. Later, after responding to the attack, he opened the straw sack and found that the boiled soybeans had become natto.

Legend 2
In Iwateyama (Miyagi Prefecture), Yoshiie made a pilgrimage to a hachiman shrine that was a Genji tutelary shrine. He was given natto by a local person and was impressed by the delicious flavor, and thereafter spread it to other areas.

Legend 3
Abe no Muneto, who had been defeated by Yoshiie's troops and had been taken prisoner, was banished to Dazaifu in Kyushu. Muneto, who was a very cultured person, was loved by the local people, and he spread the culture of his home region, Oshu, far and wide. One of these things was natto, and ever since "korumame" dried natto has been passed down in Kyushu.

Legend 4
When Yoshiie's troops were camped at Hitachi (Ibaraki Prefecture), Yoshiie saw some leftover boiled soybeans that had been left on some straw and had become discolored. "What a waste," he thought. "I wonder if they're still edible." Putting them in his mouth, he found them chewy and delicious. Thereafter, he studied how to prepare soybeans as preserved foods to eat while they were encamped, and in this way the method of preparation became established.

Legend 5
While on his way to fight the Battle of Ōshū, Yoshiie discovered when he was near Otawara (Tochigi Prefecture) that boiled soybeans in a straw bag had grown fine threads. He investigated the connection between the boiled soybeans and the straw, and established the method of preparation.

Legend 6
While Yoshiie's troops were fighting in Senboku-gun (Akita Prefecture), they suffered from extreme hunger and cold. Ordered to urgently provide food for the horses, a local farmer hastily put boiled soybeans that were still hot into straw bags and gave them to Yoshiie's men. As they were piling up the bags in a hut, they noticed that the soybeans were sticky and discolored. But when they fearfully placed them on Yoshiie's dining table, Yoshiie smacked his lips over and over again in admiration, exclaiming that the soybeans were delicious, and he recommended that all of his men taste them.

Legend 7
Soldiers that had been dispatched from Kyoto to Senboku-gun put down a rebellion on Yoshiie's orders and then returned to their home regions. There they spread the method of preparing natto that they had learned in Senboku-gun. This eventually spread to Kyoto and became the roots for the local variety of natto.