Onigiri (おにぎり)

Onigiri (rice ball) is a food, which flavored cooked rice, put fillings, and collectively shaped into triangle, rectangular rounds, or sphere.

It is also called omusubi or nigiri-meshi, or simply 'musubi' or 'nigiri' occasionally. It has many names depending on the region or home. See the name of onigiri.

In Japan, onigiri has been regarded as the staple food in a boxed lunch through all ages because it is cookable ahead and portable. Nowadays it is becoming the mainstream as a regular food, and unpreservable onigiri at room temperature is sold in convenience stores and supermarkets. As a result of recent overseas advance by major Japanese convenience stores, Japanese onigiri has been eaten around the world.


Onigiri is originally developed to preserve remains of cooked rice and as a portable food, but nowadays being easy-to-eat is added, and preserving property and portability are not highly regarded.

Onigiri as a portable food

How to make onigiri is summed up in keeping the status protecting from growth of bacteria as much as possible. The point is time, surface area, temperature, and humidity. The cautions are described as follows.

Make onigiri by just cooked hot rice. Cooked rice after passing some time is not safe to carry for a long time even if it is reheated because the number of bacterium increases (especially the toxin discharge type bacteria).

Make onigiri as solid as possible to reduce the part that contacts with the air. Or paste a sheet of dried laver from the beginning entirely in onigiri, which is made solidly to some extent and cooled down (described later). This part relates to the current commercially available onigiri being not suitable for carrying.

Attach salt to the entire surface of onigiri evenly. Coating with excessive salt and sugar is effective to prevent growth of bacteria. The current low salted onigiri is less effective.

For fillings, those excellent in preserving property and bactericidal activity are the most suitable. Preserving property in onigiri with fillings having bactericidal activity is a little higher than that in onigiri without fillings.

Cool down onigiri sufficiently to the inside before packaging. Note that cooling in a refrigerator and others occasionally cools down only the surface. Lowering the temperature is effective to prevent growth of bacteria.

Pack in the item excellent in aeration or absorption not to dampen the surface of foodstuffs by humidity coming out from onigiri. Growth of bacteria is quickened up above a certain humidity. It is important to lower humidity on the surface of onigiri as much as possible.

A cold dark place of good ventilation is most suitable for storage facilities.

Onigiri as a meal

Nowadays onigiri is eaten at various situations. Palatability, rather than portability, is asked for most of the situations.

Onigiri of soft texture in the mouth is favored.

There are a wide variety of fillings.

Strongly salted onigiri tends not to be favored. The current low salt policy and the amount of perspiration varying by occupation are related to this.

Onigiri is wrapped by a sheet of dried laver depending on the taste. For wrapping, there are also a wide variety of ways.

The name of onigiri

Onigiri is called differently depending on the region or home.

Particularly in and around Hiroshima City, Hiroshima Prefecture, both general household and food-service industry tend to call 'musubi' (also called as 'omusubi'), but of course 'onigiri' is understandable. It is also called in dialects, such as 'nigiri-mama' (Aomori Prefecture) and 'oninko' (Tochigi Prefecture). Omusubi is originally a word of court ladies in the Imperial Palace. In Japan, onigiri has a strong image of triangle and 'onigiri-shaped' is a good example of the pronoun to indicate the things triangle.
As an aside, MAZDA Motor Corporation, a car manufacturer in Hiroshima Prefecture solely producing Wankel engines, calls 'a rotor' in the engine 'omusubi-shaped.'

Differences in onigiri and omusubi

One theory says that onigiri and omusubi are different both in word origin and shapes. Onigiri is made by cooked rice regardless of the shape, but omusubi should be triangle. Three pillar gods, Ameno minakanushi no kami, Takami musubi no kami, and Kami musubi no kami appeared in Kojiki (A Record of Ancient Matters) are the names of the gods who came on for the first time after the heaven and earth divided.
The word common to these Takami musubi no kami and Kami musubi no kami is 'musubi.'
It says that this "musubi" means a holy spirit to produce all things in the universe or its spiritous power.
And the Japanese people of that time divinized mountains and ate mountain-shaped rice (the shape of the god) to receive divine power, and this is the beginning of 'omusubi.'

There are various stories regarding differences in onigiri and omusubi, such as onigiri is triangle and omusubi is rectangular rounds contrary to the above.

The other theory says that nigiri-meshi or onigiri has older history and omusubi is its word of court ladies or a formal word. Onigiri has a theory of being an effective talisman because it is similar to the word 'oni wo kiru' (wipe out an ogre), and there is a folk tale that nigiri-meshi of white cooked rice is thrown to wipe out ogres. Another theory for omusubi is that the word 'musubu' (tie) indicates ubusuna (a god) who embraces spirits and protects the earth.

Furthermore, the name of 'MUSUBI' is common rather than onigiri in some regions such as Hawaii where many immigrants moved to live in the Meiji period (1852 to 1912). This may because there were many people who came from the regions where the name of omusubi was dominant, such as Hiroshima.

Manufacturing process

It may vary depending on the region or home, but the currently most common process is described as follows assuming that they will be consumed immediately.

Dip both hands in lukewarm water, drain them lightly, coat palms with salt slightly, and take steamed rice as much as a piece of onigiri in the hands.

First press it lightly just solidifying outside and put fillings in the center.

Then shape it by rolling three or four times and pressuring evenly to arrange the shape. Note that making too soft collapses the shape and too solid ruins the texture.

In summer it is recommended to make using a sheet of kitchen wrap also as a preventive sanitation measure because bacteria in the hands such as staphylococcus aureus can grow. Furthermore, 'onigiri-shaped' plastic cases are sold in household goods stores and other places. These are the instruments to easily make onigiri simply by filling cooked rice in them.


The table manner for onigiri is to eat from the edge and trim horizontally without leaving tooth mark. Basically hold directly by hand and bring to the mouth, but using chopsticks is recommended for those of rectangular rounds in a boxed lunch.

Forms of onigiri

Shape, rice, fillings, and wrapping compose a piece of onigiri.


Though many others are possible, usual shapes are as follows:


Low-height triangle pole

Rectangular rounds

Nonangular pillar


Shape like a piece of Gouda cheese and Kagami-mochi (a round rice-cake offered to a deity)


Easy to shape because it lacks direction


Low-height square
Seen in Taiwan and other regions. Closer to oshizushi, a lightly-pressed piece of sushi with cooked ingredients on top.

There is no rule especially, but customarily divided as followings:


Ordinary boxed lunch.

Rectangular rounds

Boxed lunch at the so-called 'celebration' table.



Cooked rice

Starch in cooked japonica rice which eaten as a staple food in Japan is less stiffened even when it becomes cold. Therefore, it is more suitable for onigiri than other breeds. Low amylose rice with higher property of 'tasting good eaten cold' is often used for onigiri sold in convenience stores and others, while sticky uruchi rice eaten daily is used for those made at home.

Furthermore, 'yaki-onigiri' (grilled rice ball) is another cooking method to make onigiri, which flavored with soy source or miso (fermented soybean paste) and grilled by wood fire and others.


Many fillings are excellent with white rice and have a strong taste (also in the sense of preservation). Umeboshi (pickled plum), dried bonito flake, food boiled in soy sauce, and others are the longtime standards. Fillings are generally not included in rice cooked or mixed with ingredients, in which rice itself are already flavored.

Fillings are generally embedded in the center, but some are pasted on the surface, such as Spam, trout sushi, matsutake mushroom, and others.


Most of onigiri pieces are wrapped in a sheet of dried laver, but some in different foodstuffs. Such as Nozawana (a variation of turnip) in Nagano Prefecture, shaved kelp in Toyama, Ishikawa, and Fukui Prefectures (the largest production centers of kelp), and leaf mustard pickles in Wakayama Prefecture which show regionality, and also there is a rice omelet-like onigiri which wrapped chicken with rice with crepe-style fried egg. Some plant leaves prevent growth of bacteria and also raise preserving property.

There are various ways to wrap onigiri with a sheet of dried laver. The way to wrap is described here assuming triangle onigiri.

The way to wrap all sides of onigiri evenly

The way to paste from only one side to back and forth

The way to wrap around the sides

On the other hand, there is a technique to sprinkle dried seasoning and others without wrapping. Sesame (black or white), mashed fish, dried egg and laver seasoning, citrus and pepper, and others are used. Shio-musubi' (salted onigiri) has no filling and a small amount of sesame can be sprinkled on the surface.


Mainly a sheet of kitchen wrap, aluminum foil, Japanese paper, and others are used. It is recommended to avoid those losing colors and odiferous (including metallic-tasting) because colors and smells are easily imparted to onigiri.

Bamboo sheath

Bamboo sheath was generally used to wrap onigiri. It is more excellent in preserving property than kitchen wrap and aluminum foil because of bactericidal activity and appropriate aeration. However, nowadays not used as before because it lacks in convenience such as massive stable supply, price, and availability.

History of onigiri in Japan

A carbonized lump of rice grains which seems to be onigiri is unearthed in the Chanobatake remains of the late Yayoi period (the early first century, Rokusei Town, current Nakanoto Town, Ishikawa Prefecture) in December 1987. Initially it is reported as the oldest onigiri because the trail of pressing by human fingers were remained in this carbonized rice. The later research revealed that it was probably steamed and then grilled, rather than cooked and pressed, and closer to chimaki (a rice dumpling). Furthermore, carbonized rice which solidified like onigiri is also found in the Kitakaname Tsukakoshi remains (Hiratsuka City, Kanagawa Prefecture).

The direct origin of onigiri is considered to be a food called 'tonjiki' in the Heian period (the end of 8th century to the early 12th century). Onigiri around that time was oval, very big (225g), and steamed sticky rice was used.

Sticky uruchi rice has been used from the end of the Kamakura period (the early 14th century). Laver comes along with onigiri and a sheet of dried laver has been generally spread from the Genroku era (the end of 17th century) in the name of such as 'Asakusa dried laver,' nutritious and convenient because cooked rice does not stick to the hands, which established a relationship of laver and onigiri.

Onigiri at the present time

Onigiri is made at home and also sold on the market such as convenience stores ("CVS" hereafter) and supermarkets.

Home-made onigiri is daily eaten as a cook-ahead lunch in addition to the usage based on the original idea to be a portable meal such as a field trip lunch. It is often put in a boxed lunch. Variously shaped and one type is commonly called 'Bomb,' which shaped cooked rice into a big ball and wrapped in a sheet of dried laver. Preserving property varies depending on how it is made.

On the other hand, most of onigiri pieces sold in CVS, supermarkets, and others are produced in bulk by machines in food manufacturing factories. Forms are different in an individual package and a pack package of two or more onigiri pieces, and the former is often a 'hand-rolled dried laver' type which isolated a sheet of dried laver from the main body of cooked rice by the inner film to protect from humidity. This protection film is devised to be easily pulled out by hand when eating, and just-wrapped, crispy texture of dried laver is enjoyable all the time. Normally consumption in a short time is assumed, keeping in a refrigerator is specified, and a best-before date within a few days is clearly described.

In the mid-1980's when CVS has begun to take root in Japan, each company had own method to open a package of onigiri and the standard was not unified.
Then, Shinobu Foods Products invented a parachute type to twist (or cut) a film on the pointed top to open and pull out an inner film sheet, and sold under the catchphrase 'just-pulling onigiri Q.'
This method was often adopted for a while. In this case, however, unaccustomed hands hold only the upper part when pulling out an inner film sheet, consequently cooked rice remains in the inner film. This is why the present mainstream is a separate type to cut a film from the top along the cutoff line and separate into right and left to open. Still some consumers say that even this type is not a perfect solution because a sheet of dried laver is often torn and its pieces remain in both corners of the film, and also garbage increases by scattered outer and inner films. Therefore, not a few people are hoping for the parachute type to be back, in which a sheet of dried laver is not torn and its pieces do not remain. Meanwhile, in 2004, Lawson (the second largest CVS in Japan) put on sale a product called a 'hand-rolled square package,' which just bent a sheet of dried laver in the shape of U, but some people say it is rather difficult to remove.

Onigiri is highly regarded as the merchandise supporting a boxed lunch corner in CVS and supermarkets, and each company is fiercely fighting to develop new onigiri products and gain customers especially in CVS.

In some regions such as Okinawa Prefecture and Hokkaido, occasionally a clerk asks, 'Shall I warm it up?' when buying onigiri in CVS.

Furthermore, fast-food store like outlets and eating-out restaurants specialized in onigiri have been also opened.

Onigiri outside Japan

Onigiri is also made in China, Taiwan, South Korea, and part of Thailand, which are the same rice-producing zone as Japan. In China and South Korea, however, they have had a strong belief that 'rice should be eaten in hot' and a persistent image that cold rice such as onigiri is 'for petty people' and 'an inevitable portable meal,' and hardly eaten daily respectively calling 'fan twan' (rice dumpling) in China and 'fist rice' in South Korea. Fujian in China has a kind of onigiri called 'cǎobāofàn' which filled meat, sausage, mushroom, and others in rice and put them in a woven grass bag to carry, but quite different from the image held by the Japanese people. In Thailand, indica rice usually unsuitable for onigiri is a staple food, while in the northeastern region where sticky rice is stale food, they have a custom to carry spherically-shaped cooked rice wrapping in grass leaves traditionally.

In Taiwan, Japanese food culture including train lunch and sushi is widely known, thereby the image to onigiri is no longer as petty as before. Onigiri sold on the spot is occasionally made from sticky rice unlike those in Japan. Tastes of fillings, such as processed sweet pork and fried bread, are also a little different from those in Japan. The current popular onigiri is square and about 1.5 times larger than normal.

In Taiwan and Shanghai City, Japanese-style onigiri has become popular after CVS run by Japanese companies landed and spread. As a result, they started selling onigiri which manufactured in local factories using a closer breed to the Japanese rice. In South Korea, triangle onigiri sold in CVS is getting popular.

In Hawaii and Okinawa Prefecture, onigiri filled with Spam (luncheon meat) is sold in the name of 'Spam musubi' and 'pork egg onigiri' (oni-por), and so on. In Australia, occasionally onigiri is treated as a fast-food menu.

[Original Japanese]