Natto: Japan's Sticky Fermented Soybeans

Curious about natto? Learn how Japan's sticky fermented soybeans are made, where they come from, how to eat them, and tips for first-time tasters.

Published October 18, 2026 at 7:23 AM JST | By Tokyo Paul

Quick answer: Natto is a Japanese food of whole soybeans fermented with Bacillus subtilis var. natto, giving a sticky, stringy texture and a strong aroma. It is usually stirred with sauce and mustard and eaten over rice, especially at breakfast.

Few foods spark as much curiosity as natto. Open a small foam tray in a Japanese convenience store and you will find soybeans wrapped in glossy, stretchy strands, a savory aroma, and a tiny packet of sauce waiting to be stirred in. For many people in Japan it is simply breakfast, and for visitors it is a rite of passage. This guide explains what natto is, where it comes from, how it is made, and how first-timers can approach it with a smile.

What Is Natto?

Natto is a traditional Japanese food made from whole soybeans fermented with a helpful bacterium, Bacillus subtilis var. natto, known in Japanese as natto-kin. The fermentation gives the beans a sticky, stringy coating and a strong, earthy smell that is often compared with aged cheese. The flavor, however, is nutty, savory, and almost umami-like, which is why many fans describe it as more mellow than the aroma suggests. It is usually eaten at room temperature, spooned over hot rice.

Natto is sold in small plastic or foam containers, often in packs of two to four, and nearly every supermarket and convenience store stocks it. Each container usually includes a small sachet of soy sauce or tare sauce and another of karashi, a spicy Japanese mustard. Beans come in different sizes, and smaller beans are often preferred for natto, though larger and finely chopped varieties are also sold.

Where Does Natto Come From?

The origins of natto are wrapped in legend, and food historians say its beginnings are not settled. One popular story describes a samurai commander named Minamoto no Yoshiie, who was campaigning in northeastern Japan in the eleventh century. According to the tale, local farmers boiled soybeans for the troops and wrapped them in rice straw, and a few days later the beans had transformed into something delicious that the soldiers happily ate. Other accounts suggest natto developed independently in several places, since the ingredients and conditions were common across ancient Japan, and it may be related to salted fermented soybean seasonings from China.

Today Ibaraki Prefecture, northeast of Tokyo, is closely linked with natto, and the city of Mito is often described as its hometown. The Japan National Tourism Organization has highlighted Mito natto as a signature food of the region, and visitors to Ibaraki can find natto-themed souvenirs and dishes. In general, natto is most popular in eastern Japan, including the Kanto and Tohoku regions and Hokkaido, and it has traditionally been less common in Kansai, the area around Osaka and Kyoto, though tastes today are mixed everywhere.

How Is Natto Made?

Making natto starts with soaking soybeans for many hours until they swell, and then steaming them until tender. The cooked beans are mixed with the natto bacteria and kept warm, at around 40 degrees Celsius, for up to a day so the fermentation can develop. The beans are then chilled for a period to let the characteristic stickiness mature. Traditionally, beans were wrapped in rice straw, which naturally carries related microorganisms, but modern producers use controlled starter cultures in clean facilities, which simplified large-scale production in the early twentieth century.

The strings you see are made of long molecules produced during fermentation, and stirring them builds the foamy, fluffy texture many people like. This is why natto is traditionally stirred well, with chopsticks, before the sauce is added. The result is lighter and more spreadable, and the flavor seems to bloom.

How Do You Eat Natto?

The classic way is simple: open the container, stir the beans until they become sticky and pale, add the sauce and a dab of mustard, and spoon the mixture onto steaming white rice. Many people add chopped green onion, a raw egg yolk, or a splash of soy sauce. Natto also appears in miso soup, rolled into sushi (natto maki), spread on toast, folded into omelets, and tossed with pasta, so there are plenty of ways to explore the taste if the straightforward style feels like a leap.

Traditional Japanese breakfasts at ryokan and minshuku (family-run guesthouses) frequently include natto next to grilled fish, pickles, rice, and miso soup. If you would like to try it for the first time, an inn breakfast is a gentle setting, because the dish is served in a small portion and the other items on the tray help balance the flavor. Natto also turns up in rolled sushi and in rice dishes at casual eateries, which are other easy ways to taste it.

What Should First-Time Tasters Know?

Take a small first bite and give your palate a moment. The smell is strongest when the lid is opened, and the taste is usually milder than expected. If the stickiness is a challenge, try a version with chopped beans or mix it into a bowl of rice with egg and scallions, which softens the texture. Using chopsticks or a spoon to scrape the strings back into the bowl keeps the table tidy, and a cup of green tea afterward is a refreshing finish.

Natto is rich in vitamin K, which is a good reason for anyone taking blood-thinning medication to check with a doctor before eating it regularly. People with a soy allergy should also avoid it. Store natto in the refrigerator, check the date on the package, and follow the storage instructions printed on the package. If you are unsure about a particular product, shop staff can usually help you pick a gentle, beginner-friendly one.

A supermarket natto aisle is a good place to explore. Packs differ in bean size, and you may see whole beans, small beans, and finely chopped versions called hikiwari, which many people find easier to eat because the texture is smoother. Sauces also vary, from classic soy sauce to dashi-flavored blends, and some products come with extra seasonings. Reading the front of the package, or asking a staff member for a mild recommendation, makes it easy to pick one that suits your taste.

Quick Takeaways

Natto is a sticky, savory, nutty fermented soybean food that is deeply woven into Japan's everyday meals, especially breakfast. Stir it thoroughly, add the sauce and mustard, and enjoy it over rice with a few simple toppings. Eastern Japan and Ibaraki's Mito area are its best-known strongholds, but you can find it just about anywhere in the country.

Whether you end up loving it or simply enjoy the story, trying natto is a delicious window into how people in Japan eat. A small tray of beans can teach you a lot about fermentation, regional pride, and the pleasure of a bowl of hot rice.

Frequently Asked Questions

What does natto taste like?

Natto tastes nutty, savory and slightly umami, and is usually milder than its strong smell suggests. The texture is sticky and stringy. Stirring it well and adding soy sauce, mustard or green onion helps balance the flavor.

How do you eat natto for the first time?

Stir the beans with chopsticks until they turn pale and foamy, add the sauce and a little mustard, and spoon them over hot rice. Chopped-bean versions or a topping of egg and scallion can make a gentler first try.

Where is natto most popular in Japan?

Natto is most popular in eastern Japan, including the Kanto and Tohoku regions and Hokkaido. Ibaraki Prefecture, especially the city of Mito, is closely associated with it, while the Kansai area has traditionally been less devoted to it.