Natto: The Stringy Breakfast Japan Swears By, Explained for Beginners

Updated October 15, 2026 | By Tokyo Paul

A small foam tray, a thin plastic film, and two tiny packets: one of soy sauce, one of hot mustard. That is how natto (fermented soybeans) arrives in Japan, sold in three-packs at nearly every convenience store and set beside the rice at hotel breakfast buffets. Peel back the film, stir with chopsticks, and the beans pull into long, silky threads that stretch like cobwebs. The smell is sharp and earthy, a little like strong cheese. The first bite can be a surprise, and for many people the second is the start of a habit.

Natto has been part of Japanese eating for roughly a thousand years, and it still divides opinion at the breakfast table. It also tells a good story about how a simple farm food, a few beans and a bundle of straw, grew into a national staple with its own capital city, its own festival-like day on the calendar, and a very specific way to be stirred. This guide covers where natto came from, how it is made, how Japan really eats it, and how to try it without fear.

Two Legends and a Wooden Tag

Nobody can say for certain who made the first batch. One popular legend points to the warrior Minamoto no Yoshiie (1039 to 1106), whose troops were campaigning in northeastern Japan between 1086 and 1088. Boiled soybeans meant for the horses fermented in straw bags, the soldiers liked the taste, and they offered some to Yoshiie, who liked it too. A second story gives the credit to Prince Shotoku (574 to 622), who supposedly wrapped leftover beans in straw for his horse. Both tales are charming, and both are best treated as folklore.

The more likely history is quieter. Fermented soybean seasonings came to Japan from China, and natto may have appeared by accident while people were making them, possibly in several places at once. A wooden tag bearing the character for fermented soybeans was found at the old capital of Heijo-kyo (present-day Nara), and by the 11th century the name natto had become standard. Because it needs only beans, straw and patience, it spread easily through farming households, long before anyone knew what was happening inside the bag.

How Boiled Soybeans Become Strings

Straw carries a bacterium that thrives on hot, steamed soybeans. Modern makers use a purified culture instead: Bacillus subtilis var. natto, called natto-kin in Japanese. In the Taisho period (1912 to 1926) researchers developed a starter that did not depend on straw, and that change made large, consistent batches possible. Small soybeans are usually preferred. They are soaked for around 12 to 20 hours, steamed, mixed with the culture, and fermented at roughly 40 degrees Celsius for up to a day.

After fermentation the natto is cooled and rested, often for several days in the refrigerator, so that the stickiness and flavor develop fully. Japan's agriculture ministry notes that careful control of temperature and humidity from fermentation through maturing is the key to a good result. The finished product is usually packed in small 40 to 50 gram containers. The strings and the pungent smell both come from the fermentation itself, which is why a fresh pack and a well-stirred bowl taste noticeably different from a rushed one.

Mito, the Natto Capital

Ask anyone in Japan where natto comes from and the answer is usually Mito, the capital of Ibaraki Prefecture northeast of Tokyo. The local Mito clan encouraged farmers to grow early-maturing soybeans that could be harvested before typhoon season and the flooding of the Naka River. Those small beans were poor for making soy sauce or miso, but they suited natto well. By the Edo period (1603 to 1867) it was a common household food, eaten in soups or simply with soy sauce.

Fame arrived with the railway. When the Mito Railway opened in 1889, natto was sold on station platforms, and travelers carried it home as a souvenir. Traditional forms still exist: natto wrapped in rice straw (warazuto), natto packed in thin pine-wood boxes (kyogi), and dried natto (hoshi natto) that crunches like a savory snack beside tea or sake. Informally, July 10 is celebrated as Natto Day, because the numbers can be read as na and to, which together sound like the word natto.

Taste, Smell and Texture, Described Fairly

Natto tastes savory and slightly nutty, with a deep soy flavor and a faint bitterness. The texture is soft inside the beans and gooey around them. The smell is the real hurdle: something between ripe cheese and roasted earth. Japanese people are divided about it too. A 2009 survey of 3,827 respondents found that around 70 percent considered the taste pleasant, while others eat it mostly out of habit. In other words, you will not be the only person at the table making a face.

The standard method softens the experience. Stir the beans before adding anything, then add the soy sauce and a dab of karashi (Japanese hot mustard) from the packets, and stir again until the strands turn pale and fluffy. The mustard cuts the smell and adds a pleasant kick. Spoon it over hot rice rather than eating it alone, because the plain rice calms the flavor and makes the sticky texture feel natural. If the first attempt is not for you, a second try with more mustard and more rice often changes the verdict.

How Japan Actually Eats It

The classic form is natto gohan: cold natto on hot rice, often with chopped negi (long green onion) on top. Some people stir in a raw egg yolk or a spoonful of kimchi, and others add a splash of dashi-flavored soy sauce. It shows up at breakfast in homes, ryokan (traditional inns), and hotel buffets, usually in a small bowl beside miso soup and grilled fish. For many households it is the fastest, cheapest protein on the table.

Cooks also treat it as an ingredient. Natto turns up in sushi rolls (natto maki), on toast, in miso soup, folded into tamagoyaki (rolled omelet), inside okonomiyaki, in fried rice, and even over spaghetti. Fried and dried versions, developed around 1990, have less smell and less stickiness, which makes them a gentle way in. Another option is a milder variety bred to be less sticky. Convenience stores sell several styles, so it is easy to compare without committing to a full restaurant meal.

East Versus West, and a Note on Nutrition

Natto is most popular in eastern Japan, including the Kanto region around Tokyo, the Tohoku region, and Hokkaido. It has traditionally been less loved in the Kansai region around Osaka and Kyoto, and the east and west rivalry over it is a familiar piece of Japanese small talk. Today, national supermarket distribution has softened the divide, but plenty of people from the west still pass on the pack. Visitors need not feel pressure either way.

On the nutrition side, a 50 gram serving provides roughly 110 calories and plenty of protein, iron and manganese, along with a very high amount of vitamin K. That last point matters for anyone taking blood-thinning medication such as warfarin, who should ask a doctor before eating it. It is also made from soy, so anyone with a soy allergy should avoid it. For most travelers it is simply a cheap, filling food that Japan has trusted for centuries.

Plan Your Visit

The easiest place to try natto is a hotel breakfast buffet, where it sits beside the rice with the mustard and sauce ready. For something quicker, buy a three-pack at a convenience store, usually for a few hundred yen at most, and ask for a spoon or use the chopsticks. Prices vary by brand and store. Start with a small portion over rice, stir longer than feels necessary, and keep the green onion on hand. If you are heading to Mito, the city celebrates its natto heritage and sells regional versions as gifts.

The straw-wrapped and pine-box styles are harder to find outside Ibaraki, so a souvenir shop near Mito Station is the right place to look for them. Check labels if you have a soy allergy, and keep in mind that the smell is strong enough that eating it on a crowded train is poor manners. Treat it as a small cultural experiment: one pack, stirred well, over hot rice, is a fair test. Rules and prices can change, so confirm anything specific with the shop or hotel.