Wooden barrels. Whole soybeans and wheat grown in Japan. A long fermentation and aging process spanning two or more summers.
When you hear “traditional Japanese soy sauce,” is that roughly the picture that comes to mind? We often see soy sauce presented this way in books about Japanese food and in food shows outside Japan.
There is no statistic that tells us how much soy sauce meets all of these conditions. But even one condition alone—brewing in wooden barrels—accounts for only around 1% of production, according to industry estimates. Add Japanese-grown ingredients and a long aging period, and the field narrows further.
Most other soy sauce is produced efficiently, with the aim of delivering consistent flavor year after year, in large quantities and at an affordable price. This is not a question of one being good and the other bad; they are working toward different goals.
“Handmade,” “natural,” “authentic,” “freshly pressed”—soy sauce is described in all sorts of ways. Yet those words do not always make it easy to understand how a particular bottle was made.
In this article, we will look at ingredients, production methods and industry figures to get an overview of how Japanese soy sauce is made. We will also place the soy sauces we carry at Nagahama 88 within that wider picture.
How soy sauce is classified: method, style, soybeans
First, the basics. Much of the information on a Japanese soy sauce label can be organized along three axes.
1. Method
| Method | How it is made | Share of shipments |
|---|---|---|
| Honjozo (brewed)* | Soybeans and wheat are made into koji, then mixed with brine to form a mash, which is fermented and aged | ~90% |
| Kongo jozo (blended brewing) | Amino acid liquid or a similar seasoning liquid is added to the mash before further fermentation and aging | ~0.5% |
| Kongo (blended) | Amino acid liquid or a similar seasoning liquid is added to honjozo or kongo jozo soy sauce | ~10% |
The honjozo description above refers to a typical koikuchi soy sauce.
Amino acid liquid is a seasoning liquid made by breaking down plant proteins, such as those in soybeans, with hydrochloric acid. Separate seasoning liquids made through enzymatic breakdown or fermentation may also be used (Ministry of Agriculture, Forestry and Fisheries, in Japanese). Honjozo does not use these seasoning liquids; it develops its umami through brewing. Whether other additives are used is a separate question, which the ingredient list can answer. Alcohol may be added to improve shelf life, but this does not change the production category.
Within honjozo, there is a further labeling distinction. Only honjozo soy sauce made without enzymes such as cellulase added to accelerate brewing, and without designated food additives, may be labeled tennen jozo, or “naturally brewed,” under Japan’s Food Labeling Standards. Added alcohol is permitted.
Soy sauce ⊃ honjozo (about 90%) ⊃ tennen jozo (honjozo made without enzymes added to accelerate brewing or designated additives)
The tennen jozo label does not, by itself, promise wooden barrels, Japanese-grown whole soybeans or long aging. For those details, we need to look at ingredients and the information provided by each brewery.
2. Style
| Style | Main characteristics | Share of shipments |
|---|---|---|
| Koikuchi (dark) | The most common style of soy sauce | ~85% |
| Usukuchi (light) | Pale in color, with a somewhat higher salt content | ~11% |
| Tamari | Made mainly from soybeans; thick and rich | ~2% |
| Saishikomi (double-brewed) | Brewed with soy sauce in place of brine | ~1% |
| Shiro (white) | Made mainly from wheat; very pale | ~0.6% |
(All shares are from the Japan Soy Sauce Brewers’ Association’s 2024 figures. Total shipments were about 680,000 kiloliters.)
Among these styles, soybean-based tamari preserves something of the older forms of soy sauce made before the Edo period. Methods combining soybeans and wheat gradually developed, and koikuchi and usukuchi spread during the Edo period.
That was a major innovation in its own right—but its story can wait for another time.
3. Soybeans
Whole soybeans (maru-daizu) or defatted soybean meal: the ingredient list tells you which is used. Defatted soybean meal is made by crushing soybeans and extracting their oil with a liquid that dissolves it. Soy sauce made with defatted soybean meal can still be honjozo.
The most common soy sauce in Japan is honjozo koikuchi. So far, that is not very far from the familiar picture of soy sauce. The picture changes when we look at the ingredients and the time involved.
About 80% of the soybeans have had their oil removed
By weight, whole soybeans accounted for about 19% of the soybeans used to make Japanese soy sauce in 2024, with defatted soybean meal converted to its original whole-bean weight. About 80% was defatted soybean meal. Japanese-grown whole soybeans accounted for about 6,500 metric tons, or roughly 4% of the total, according to the Japan Soy Sauce Brewers’ Association. These are shares of raw ingredients by weight, not shares of finished soy sauce shipments, but they show how small a proportion Japanese-grown whole soybeans represent.
According to the Soy Sauce Information Center (in Japanese), nearly all the soybeans, about 80% of the wheat and about 90% of the salt used for Japanese soy sauce are imported.
There are reasons for using defatted soybeans. Oil from whole beans rises to the surface of freshly pressed raw soy sauce, or kiage, and has to be removed. Taking the oil out beforehand allows the protein to be used efficiently, while the extracted oil becomes cooking oil. For a typical koikuchi, the mash is then fermented and aged under temperature control for about six to eight months.
From home kitchens to restaurants and processed foods, the goal is to deliver consistent flavor every year at an affordable price. Efficiently produced soy sauce is a highly developed answer to that need.
Shrinking at home, brewed locally abroad
The soy sauce market itself is changing, too.
Japan’s soy sauce shipments, including exports, peaked in 1973 at about 1.29 million kiloliters. In 2025, they were around 670,000—roughly half that volume, and the lowest level in 75 years, since 1950. These are the association’s figures, as reported by Kyodo News (in Japanese) in September 2026. The number of soy sauce companies or plants also fell, from about 6,000 in 1955 to 1,013 in 2024.
Overseas demand, by contrast, has been growing with the popularity of Japanese food. In 2022, Japanese soy sauce companies produced about 310,000 kiloliters at factories outside Japan—more than seven times the roughly 40,000 kiloliters exported from Japan that year (nippon.com, in Japanese). Most soy sauce from Japanese manufacturers consumed overseas is produced outside Japan.
One brewery does not always handle every step
Here is something that may surprise even Japanese readers.
In Japan, there is a division of labor in which cooperative plants jointly produce freshly pressed kiage soy sauce. Individual breweries take that kiage, adjust the flavor, heat-treat it and bottle it. A leading example is the “Fukushima method,” which began in Fukushima in 1964 and became a model for cooperative plants elsewhere. Each brewery determines its own flavor during the finishing stages.
This arrangement allows small breweries to share equipment and sustain regional soy sauce traditions. Other breweries handle every step themselves, from choosing ingredients to pressing the mash. The brewery name on the label alone does not tell you which approach is used.
Where our shelf sits on the map
Here are the soy sauces we carry at Nagahama 88.
Kajita Shoten, in Ozu, Ehime Prefecture, on the island of Shikoku, has records dating back to 1874. All the soy sauce it sells is brewed in-house. Within its range, the Tatsumi line uses soybeans and wheat grown entirely in the local Nanyo region, with salt from Naruto in Tokushima Prefecture. Tatsumi is brewed without added yeast or enzymes, in cedar barrels that have been in use for more than a century.
- Tatsumi Naturally Brewed Whole-Soybean Soy Sauce — Koikuchi (Dark): fermented and aged for at least 18 months, spanning two summers.
- Tatsumi Naturally Brewed Whole-Soybean Soy Sauce — Usukuchi (Light): fermented and aged for about one year.
- Saishikomi Soy Sauce “Kajita Yasutsugu”: two-year-old Tatsumi koikuchi is used in place of brine for another koji mash, which is fermented and aged for two more years. This is not koikuchi simply left to age for four years, but a soy sauce made in two stages over four years in total.
Tokai Jozo, in Suzuka, Mie Prefecture, makes tamari in wooden barrels it has used since the Taisho era (1912–1926).
- Sokobiki Tamari: aged for five years and made without wheat. It is neither pressed nor heat-treated; the tamari is collected as it drips from the bottom of the barrel.
Soy sauce brewed in wooden barrels is estimated to account for around 1% of production, based on barrel counts, according to Shokunin Shoyu (in Japanese). Here is how our shelf looks along the axes introduced earlier.
| Axis | Typical industry practice | The soy sauces at Nagahama 88 |
|---|---|---|
| Method | Honjozo (~90%) | Tennen jozo |
| Soybeans | About 80% defatted; mostly imported | Whole, locally grown |
| Aging | About 6–8 months for typical koikuchi | About 1 year (Tatsumi usukuchi) to 5 years (Sokobiki Tamari) |
| Vessel | Mostly tanks | Wooden barrels |
| Style | Koikuchi accounts for about 85% | Koikuchi and usukuchi, plus tamari (~2%) and saishikomi (~1%) |
Seen this way, the soy sauces on our shelf sit some distance from the mainstream. But being in the minority does not make them better. How do you meet demand on a large scale? How does production respond to changes in society? We see today’s industry as the result of responding to the needs of each era. Within that landscape, a small shop like ours chooses producers whose values we share.
Next time you are choosing soy sauce, take a look at the label. Is the style koikuchi, usukuchi or tamari? Is the method honjozo, kongo jozo or kongo? If it is honjozo, does it also say tennen jozo? Some soy sauces meet those conditions without using the label. Are the soybeans whole or defatted? Is amino acid liquid listed?
On Japanese labels, those terms appear as 濃口 (koikuchi), 淡口 (usukuchi), たまり (tamari), 本醸造 (honjozo), 混合醸造 (kongo jozo), 混合 (kongo), 天然醸造 (tennen jozo), 丸大豆 (whole soybeans), 脱脂加工大豆 (defatted soybean meal) and アミノ酸液 (amino acid liquid).
Understanding what lies behind the label gives us more to notice when tasting, and more enjoyment in choosing a bottle.
Learn, taste and choose what you find delicious. Each choice reaches a producer and helps sustain different flavors and ways of making food. We believe those choices, added together, enrich our food culture.
The thinking behind aging
Finally, a story about aging that the numbers on a label cannot fully explain.
When we visited Kajita Shoten, we heard why they bring Tatsumi koikuchi’s aging to a close at around two years. They explained that the amino acid content rises steadily up to that point, but around then, conversion to pyroglutamic acid causes the increase to level off.
This conversion is a reaction in which glutamic acid—a source of umami—and the related amino acid glutamine form a ring structure, becoming pyroglutamic acid. Pyroglutamic acid does not have the umami taste of glutamic acid. During aging, umami compounds do not simply keep accumulating: their levels reflect the balance between what is formed and what is converted into something else. Kajita Shoten explained that these changes inform its decision to end Tatsumi koikuchi’s aging at around two years.
Meanwhile, Tokai Jozo’s Sokobiki Tamari, on the same shelf, is aged for five years. Different styles, methods and intended flavors call for different lengths of time. We have not yet visited Tokai Jozo, and look forward to one day hearing directly about the thinking behind that aging period.
Next: what happens as soy sauce ages?
Compounds with “pyroglutamic acid” in their names do not all play the same role in taste. Small peptides—molecules made of two or more linked amino acids—with a pyroglutamic acid residue at one end have been found to enhance the umami of soy sauce (in Japanese). What forms during aging, and what changes? Is umami determined simply by the amount of glutamic acid?
Next time, we will explore the flavor of naturally brewed soy sauce through some very small molecules: taste-active peptides and amino acid derivatives.
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Products in this article
Tatsumi Naturally Brewed Whole-Soybean Soy Sauce — Koikuchi, 720ml
Naturally brewed for at least 18 months, spanning two summers. An everyday bottle.
- Producer: Kajita Shoten (Ozu, Ehime)
- Available: in store / online store
View Tatsumi Koikuchi in our online store
Tatsumi Naturally Brewed Whole-Soybean Soy Sauce — Usukuchi, 720ml
Aged for about a year. The brewery describes its aim as keeping the flavor of koikuchi as intact as possible while making the color lighter.
- Producer: Kajita Shoten (Ozu, Ehime)
- Available: in store / online store
View Tatsumi Usukuchi in our online store
Saishikomi Soy Sauce “Kajita Yasutsugu,” 720ml
Soy sauce brewed with soy sauce in two stages, over four years in total.
- Producer: Kajita Shoten (Ozu, Ehime)
- Available: in store / online store (may be awaiting restock)
View Saishikomi “Kajita Yasutsugu” in our online store
Sokobiki Tamari, 100ml
Aged for five years in wooden barrels, neither pressed nor heat-treated. Made from soybeans without wheat.
- Producer: Tokai Jozo (Suzuka, Mie)
- Available: in store / online store