Nakasada Shoten’s 140-Year Craft of Soybean Miso & Tamari
Apr 17,2025
Apr 17,2025
For 140 years, Nakasada Shoten has been making soybean miso with only soybean koji malt and salt, and tamari soy sauce, a dark and rich-tasting soy sauce produced as part of the soybean miso-making process. To learn about the company’s painstaking production method and the secret to its taste, we visited the town of Taketoyo on Aichi’s Chita Peninsula and spoke with Nakagawa Yasunori, the sixth-generation owner of Nakasada Shoten.
The miso used to make red miso soup is called red miso or red dashi stock miso. But do you know how this miso is made? The rice miso used in most parts of Japan is made from soybeans, rice koji, and salt. Red miso, however, is made from just soybeans and salt. This miso is referred to as soybean miso, since it doesn’t use rice, and is primarily consumed in the Tokai region. Soybean miso is used in common Aichi dishes such as miso katsu [pork cutlet with miso sauce] and miso oden [simmered vegetables and meat in miso broth].
For this article, we visited Nakasada Shoten on Aichi’s Chita Peninsula, a miso brewery that continues to produce soybean miso using traditional methods. The tamari soy sauce that seeps out during the soybean miso production process is another signature Nakasada Shoten product. “They may have an unfamiliar taste at first, but once you understand their deliciousness, there’s no going back. That’s how rich in umami flavor soybean miso and tamari soy sauce are,” says Nakagawa Yasunori, the sixth-generation owner of Nakasada Shoten. He began by giving us a tour of the storehouse where the soybean miso and tamari soy sauce are made.
Nakagawa Yasunori, the sixth-generation owner of Nakasada Shoten
“Soybean miso and tamari soy sauce are made with just soybean koji and salt. First, we wash the soybeans, place them in a pressure cooker with water, and steam them for several hours. We cool the softened soybeans to about 40 degrees Celsius and then roll them into balls called miso balls. For the soybean miso, we coat the surface of these miso balls with starter koji and let the koji mold proliferate in a special koji room to create the soybean koji.”
Forming miso balls and coating them with koji mold is a step particular to making soybean miso. We asked Nakagawa why they form the miso balls.
“It is very common to have natto bacteria in the air around us. Since soybean miso uses soybeans as its main ingredient, it can easily turn into natto [fermented soybeans] should the temperature range change. In practice, koji mold proliferates at temperatures in the low 30s, while natto bacteria tend to thrive when the temperature reaches 40 degrees. Because of this, we form the steamed soybeans into miso balls to reduce their surface area, making it harder for bacteria to multiply on them. As an added benefit, shaping them into round balls creates an environment conducive to producing lactic acid bacteria. When lactic acid bacteria proliferate in the miso balls, they create an acidic environment that inhibits natto bacteria growth. This prevents unwanted bacteria from infiltrating the miso balls.”
“The miso balls look like this,” says Nakagawa. “These are smaller than the actual balls because they have dried out.”
While on the subject, hatcho miso, a dark variety of soybean miso that has been made in Okazaki, Aichi, for ages, also involves forming similar miso balls. The miso balls made for hatcho miso are even larger than those made at Nakasada Shoten. The larger size means more lactic acid bacteria is produced, which gives hatcho miso its distinctive sourness that is stronger than typical soybean miso.
It’s unclear whether artisans long ago understood the workings of lactic acid bacteria. Nevertheless, as Nakagawa says, “through experience, the artisans of old likely arrived at making miso balls as a method to suppress natto bacteria and achieve stable fermentation of soybean koji.”
The miso balls are kept at a temperature in the low 30s for about two days to allow the koji mold to multiply steadily. They are then removed from the koji room and move on to the aging process in wooden vats.
“We let the miso age in these wooden vats.”
The area Nakagawa ushers us into is lined with large wooden vats. The vats have been in continuous and careful use since the company’s founding in 1879.
“We pack the soybean koji in the form of the miso balls we just saw into these wooden vats, add brine, and then stomp them down with our feet. Stomping down with our feet pushes out the air, creating an environment where contaminants cannot enter. We repeat this process multiple times until the soybean koji from the miso balls fills the vats to the top. Then we lay a cloth over the mixture and place stones on top to weigh it down.”
Looking down from above, you can indeed see stones laid out closely together on the top of the wooden vats.
“The stones weigh roughly 10 to 15 kilograms each, and we stack them in two layers. So one vat is covered with about 150 stones, which adds up to around 1.5 tons of weight. It’s extremely labor-intensive work requiring all our employees, but we have continued to follow this method in the same way since the company was founded.”
This process produces soybean miso. The liquid that emerges from the soybean miso during the aging process is tamari soy sauce.
“In the past, they made soybean miso and extracted the tamari soy sauce from it. But now we make the soybean miso and the tamari soy sauce separately. The reason is we want to create the very best soybean miso by not extracting the tamari from it.”
The prepared miso is left to age and ferment slowly in the wooden vats for some two to three years before it is finally ready. Tamari soy sauce undergoes a similar process and then is pressed out from the miso at the very end. Not heat-sterilizing the miso is another long-standing commitment that has been passed down at Nakasada Shoten.
“I believe these stones were brought here from the upper reaches of the Kiso Three Rivers,” says Nakagawa. The stones, which were collected when the company was founded, continue to be carefully cleaned and used today.
This Brewing Heritage Hall was built by the fifth-generation owner of Nakasada Shoten. It displays the tools and equipment used long ago as a way to pass on time-honored production methods to the present.
“Tamari soy sauce is produced through the highly inefficient method of pressing soybean miso. Soybean miso is hard, yielding relatively little liquid. Nevertheless, the liquid that we do get is packed with concentrated umami components. That’s why tamari soy sauce has such strong, delicious umami.”
Nakasada Shoten produces several types of tamari soy sauce. The company’s flagship products, however, are Tomizu and Genzo, created by varying the ratio of water used in the fermentation process, which offer luxuriously rich flavors.
“Tomizu is a tamari soy sauce brewed with ten parts water for every ten parts soybeans. Genzo, meanwhile, is brewed with five parts water for every ten parts soybeans. Regular soy sauce is typically brewed with fourteen parts water to ten parts base ingredients, making Tomizu already quite rich in comparison. Genzo — brewed with only five parts water — offers even more concentrated umami for a premium taste experience.”
After listening to Nakagawa’s description, we sampled each tamari soy sauce in turn. From our tastings, it was clear what he means by a robust umami. Unlike typical soy sauce, these offered a complex flavor profile that was more than just saltiness.
“An example of a simple way to enjoy tamari soy sauce is to use it to make seasoned eggs, which are incredibly flavorful. It’s perfect for egg over rice, which our customers love. I’d really like people unfamiliar with tamari soy sauce or soybean miso to give these dishes a try.”
As he told us this, Nakagawa mentioned a new trend among his customers that he’s noticed in the last few years.
“I used to think that soybean miso was something only Tokai locals ate because of its strong association as a regional flavor. But we’ve seen a large uptick in online and other purchases by people from around the country in recent years. We are also seeing demand from overseas. Tamari soy sauce, unlike regular soy sauce, doesn’t use barley, so it turns out that people who prefer gluten-free options are choosing it. It is well received at miso-making workshops too.”
While overall domestic consumption of soybean miso is on a slow downward curve, more people are being captivated by the flavors crafted with Nakasada Shoten’s carefully selected ingredients.
Nakagawa, himself, takes pride in the taste and robust umami of Nakasada Shoten’s products.
[Top photo] Honzo, Nakasada Shoten’s direct sales outlet, offers Nakasada Shoten products and collaboration products for sale.
[Bottom photo] Nakasada Shoten’s Houzan soybean miso, made using domestic soybeans and traditional production methods, has many fans who insist on nothing else but Houzan miso.
“Although the traditional handmade methods take more time, machines generate heat from friction that can potentially compromise our flavors. We believe continuing the same methods passed down to us is what maintains the taste of our products. We intend to keep making our products with these traditional methods.”
Despite his mild expression, Nakagawa’s powerful words convey a firm resolve to pass on this unchanged deliciousness to future generations.