"Chicken Mayo, Tsuna Mayo, Don't Steal My Heart" The History of Japanese Triangle Kimbap with Its Own Anniversary [Nichiyobi Nichi Culture]

Rice Balls Eaten Since the Yayoi Period... Rice Ball Day Established to Commemorate Fossil Discovery
Seven-Eleven is the Original Convenience Store Triangle Kimbap... Also Invented Tuna Mayonnaise Flavor

Do you like triangular kimbap? I have always believed that tuna mayonnaise is the fundamental flavor for triangular kimbap. So much so that in recent social networking services (SNS), among the Korean '3 Major Mayo Series' that Japanese people imitate?'Chicken Mayo, Tsunamayo (the Japanese expression for tuna mayo), and Don't Steal My Heart'?this tuna mayonnaise is included.

Why suddenly talk about triangular kimbap? This week, Japan celebrated the rice ball anniversary, "Onigiri Day." As the origin country of convenience store triangular kimbap, Japan designated June 18th as Rice Ball Day every year. So, I would like to take this opportunity to share stories about triangular kimbap and Japanese rice balls.

Photo by Irastora.

Japanese Rice Balls Found as Fossils from the Prehistoric Era

First, let me explain why June 18th became Rice Ball Day. In 1987, in Rokusei Town, Ishikawa Prefecture on the Noto Peninsula?which suffered great damage from this year's earthquake?the oldest rice ball fossil in Japan was excavated. It is estimated to be from the Yayoi period. The Yayoi period can be called Japan's Bronze and early Iron Age. Since bronze and iron tools existed, agriculture was possible, allowing people to make and eat such food. In short, Japan regards this as evidence that rice balls existed in prehistoric times. The 'Roku' in Rokusei Town is pronounced as the number 6 in Japanese, and combining it with the 18th day of each month, known as 'Rice Eating Day,' June 18th was designated as the anniversary to honor the oldest rice ball in Japan.

Fossilized Yayoi period rice ball excavated in Ishikawa Prefecture. (Photo by Ishikawa Digital Museum website)

The Origin of Onigiri and Omusubi: Rice Balls Offered as Sacrifices

Rice balls are called onigiri (おにぎり) or omusubi (おむすび) in Japanese. One story says the name comes from the Japanese word for gripping with the hand, but another meaning is that rice balls were offered as sacrifices. First, onigiri is said to derive from the compound of 'oni (鬼),' meaning demon, and 'kiri (切り),' meaning to cut. There is a folktale that rice balls were thrown to drive away demons, so rice balls were believed to have the effect of warding off evil.

The 'musubi' in omusubi means 'tying' or 'knotting.' It is generally used with a positive meaning, symbolizing forming good relationships between people. In Japan, there is a creator deity called Musubi no Kami who governs connections. Perhaps because of this, rice balls were once offered as sacrifices to gods. Especially, mountains have traditionally been regarded as gods, so rice balls shaped like triangular mountains were called omusubi.

Nowadays, the terms are used almost interchangeably. Depending on the convenience store, the naming differs. Most rice balls at FamilyMart in Japan are generally called musubi, while at Seven-Eleven, those where the seaweed is wrapped just before eating are called onigiri, and other products are called musubi. There is also a story that rice balls made by hand are onigiri, while those wrapped in something or made using tools are classified as musubi.

Especially, the names and shapes vary by region. The triangular kimbap shape we know today is called Kanto-style rice ball. There is also a theory that in eastern Japan, rice balls are called onigiri, while in western Japan, they are called omusubi.

Various rice balls handled by FamilyMart Japan. (Photo by FamilyMart website)

Seven-Eleven is the Originator of Convenience Store Triangular Kimbap... 2.1 Billion Sold Annually

So when did the convenience store triangular kimbap familiar to us come about? It dates back 50 years to Japan. When the first Seven-Eleven store opened in 1974, they were already selling rice balls. The reason was that although it was common knowledge at the time that rice balls were usually made and eaten at home, they thought, 'Since everyone's life is getting busier, there must be a clear need to buy and eat them outside,' so they treated them as products. However, at that time, the perception that rice balls could be bought was not widespread, so only about 2 to 3 were sold per day.

Seven-Eleven then considered how to differentiate their product. Since rice balls made at home are wrapped in seaweed from the start, by the time they are eaten at work or school, the seaweed absorbs moisture and becomes soggy. To prevent this, Seven-Eleven developed a film packaging that separates the rice and seaweed so that the crispy seaweed can be wrapped around the rice just before eating. This differentiated their rice balls from homemade ones by offering crispy seaweed.

Moreover, tuna mayonnaise has been sold since 1983, and Seven-Eleven was the first to sell tuna mayonnaise rice balls at convenience stores. The person in charge of rice ball development saw their child at home putting mayonnaise on rice and thought, 'Why not add mayonnaise?' This combination became popular immediately upon release. Currently, about 2.1 billion triangular kimbap are sold annually at Seven-Eleven in Japan.

Tuna mayonnaise rice ball from Japan's Seven-Eleven. (Photo by Seven-Eleven website)

So what rice ball ingredients are popular in Japan? According to Japan Ranking.com, Seven-Eleven's tuna mayonnaise is an undisputed steady seller. Looking at recent voting results, cooked salmon seems to be gaining popularity. The number one is FamilyMart's salmon rice ball. Second is Seven-Eleven's Japanese-style tuna mayonnaise. The savory tuna mayonnaise combined with Japanese soy sauce flavor is a very popular menu item. Third is Lawson's grilled salmon belly rice ball. In the past, salmon in convenience store triangular kimbap was all shredded finely, but Lawson puts grilled salmon whole, which provides a good texture. Fourth is FamilyMart's chicken mayonnaise, and fifth is Seven-Eleven's grilled red salmon rice ball.

Other Japanese rice ball ingredients that are hard to find in Korea include pollock roe mayonnaise, shrimp mayonnaise made by coating cooked shrimp with mayonnaise, natto, kelp, umeboshi (pickled plum), and salmon roe.

Just as we find Japanese convenience store triangular kimbap fascinating, my Japanese friends often go on convenience store tours when they visit Korea. There are many menus unique to Korea, such as Jeonju bibimbap, tuna kimchi, and Spam kimchi triangular kimbap. It is truly amazing how such diverse food cultures can be contained in just one rice ball.