Natto-jiru is a traditional winter soup that has been enjoyed in Yamagata Prefecture for generations. Natto, or fermented soybeans, is mashed into a paste and added to miso soup, creating a distinctive richness and slightly thick texture that makes this dish especially comforting during the cold season.
In the snowy Mogami region, natto was once an important source of food during winter, when fresh ingredients were often difficult to obtain. Natto-jiru combines locally available ingredients such as tofu, deep-fried tofu, wild mountain vegetables, and mushrooms, reflecting the food culture that helped people endure Yamagata’s harsh winters.
One of the defining characteristics of natto-jiru is that the natto is not simply added whole to the soup. Instead, it is thoroughly mashed in a mortar or similar utensil until it becomes a paste before being mixed into the broth.
This allows the natto to blend smoothly into the soup, creating a rich flavor and pleasantly thick mouthfeel. The sticky texture of natto is also traditionally said to help the soup retain its warmth, making it particularly welcome during Yamagata’s snowy winters.
The savory flavor of fermented soybeans combines beautifully with miso, while wild vegetables and mushrooms add further depth and texture to the soup.
In the past, it was common for households in Yamagata to make their own natto to supplement food supplies during winter. Cooked soybeans were placed in tubes or bundles made from straw and kept in a warm place for one or two nights, allowing them to ferment naturally.
The resulting natto was an important preserved food during the winter months. Preparation methods and eating habits varied from one community to another. In places such as Oe Town, for example, a tradition of using non-stringy natto in natto-jiru has also been passed down.
Natto-jiru contains much more than natto. Depending on the household and region, common ingredients include tofu, deep-fried tofu, wild mountain vegetables, dried taro stems, konnyaku, mushrooms, green onions, and seri, a Japanese water dropwort.
Among these ingredients, imogara, or dried taro stems, is particularly important. Imogara is made by drying the stems of taro varieties such as Karatori-imo. Because dried stems can be stored for long periods, they were a valuable winter ingredient in rural communities.
The combination of tofu, deep-fried tofu, natto, and other soybean-based ingredients reflects the practical food wisdom that supported everyday life through Yamagata’s long winters.
First, ingredients such as rehydrated imogara, mushrooms, wild mountain vegetables, and seri are simmered to prepare a miso-based soup. Tofu, konnyaku, and deep-fried tofu may also be added.
Natto is thoroughly mashed with a mortar and pestle until it becomes a smooth paste, then stirred into the soup. As the natto blends into the broth, its savory flavor and natural stickiness create the characteristic richness and thickness of natto-jiru.
The ingredients and seasonings vary from household to household and from region to region. This diversity is part of the appeal of natto-jiru, with each family and community having its own version of this traditional winter dish.
Natto-jiru is enjoyed not only as an everyday winter meal but also as part of annual celebrations and traditional events. In some parts of Yamagata, it is traditionally eaten around January 7, during the time of Nanakusa, the traditional Seven Herbs Festival, sometimes in place of the more widely known nanakusa-gayu rice porridge.
There are also communities where natto-jiru is served during local observances such as Daikoku-sama no O-toshiya on December 9, a traditional event honoring Daikoku-sama, one of Japan’s household deities associated with prosperity and good fortune.
In areas including Mogami and Shonai, natto-jiru has been preserved as part of local seasonal customs. Sharing a bowl of hot soup with family during the coldest months is a simple way to experience the relationship between Yamagata’s food culture, climate, and traditional way of life.
Natto-jiru has a long history, and it is believed to have been widely eaten in Japan by the Edo period (1603–1868). Natto-jiru appears in “Rikyu Hyaku-e Ki,” a record of tea gatherings associated with the famous tea master Sen no Rikyu. There are also accounts stating that Toyotomi Hideyoshi ate natto-jiru at one of Rikyu’s tea gatherings.
In Edo-period Japan, natto served in soup may have been more common than the familiar modern combination of natto and rice. This highlights how the way natto was enjoyed has changed over the centuries.
“Morisada Manko,” a record of customs and everyday life from the late Edo period, also contains descriptions of natto and how it was consumed.
The records indicate that in colder regions, natto was used as a food source when vegetables and other ingredients became scarce during winter. In Edo, meanwhile, natto was also sold during the summer.
Natto could be eaten by simmering it in soup or simply seasoned with soy sauce, suggesting that different regions and communities had their own ways of enjoying it. In Kyoto and Osaka, homemade natto was reportedly more common, while commercially sold natto was less widespread.
In earlier times, it was common to see natto sellers walking through towns and neighborhoods selling freshly prepared natto. They would carry fermented soybeans and call out “Natto~ natto!” as they made their rounds in the morning.
These natto vendors also appeared in traditional comic poetry known as senryu, reflecting the close connection between natto and breakfast in everyday life at the time.
Although such street vendors are rarely seen today, memories of this food culture remain part of the long history of natto and dishes such as natto-jiru.
Natto-jiru is not unique to Yamagata. It has also traditionally been enjoyed in other parts of the Tohoku region, including Iwate and Akita prefectures. Ingredients, seasonings, and the occasions on which the soup is eaten vary from one area to another.
Within Yamagata itself, natto-jiru is enjoyed in places such as Yamagata City, Shinjo City, Shonai Town, and Sakata City. Every household and community may have its own combination of ingredients and distinctive flavor.
For visitors to Yamagata, trying natto-jiru in winter offers an opportunity to experience a traditional food culture shaped by the snowy climate and the practical wisdom of life in a northern region of Japan.
Natto-jiru is also recognized as a “winter seasonal word” in Japanese haiku. Its warm broth, enriched with the savory flavor of natto and filled with mountain vegetables and mushrooms, naturally evokes the atmosphere of the cold season.
Born from the ingenuity of people living in snowy regions, natto-jiru makes skillful use of preserved foods and ingredients that could be stored or gathered locally. A bowl of this hearty soup offers a taste of Yamagata’s traditional food wisdom, seasonal life, and comforting home cooking.
Winter