Onigiri Day (Onigiri no Hi)

What Is Onigiri Day?

June 18 is "Onigiri Day" each year. In 1987, a lump of carbonized rice from the middle Yayoi period (about 2,000 years ago), nicknamed Japan's oldest "onigiri fossil," was discovered at the Sugitani Chanobatake site in Rokusei Town, Ishikawa Prefecture (now Nakanoto Town). Rokusei Town created the day to promote itself as "the home of onigiri." The date combines the "roku" (6) of Rokusei with the 18th, which is "Rice Eating Day" every month. It's a day to look back on the history of onigiri — a cornerstone of Japanese food culture — and to reflect on the goodness and importance of rice.

A History Stretching Back 2,000 Years

Onigiri has long been a portable food supporting daily life in Japan.

• The Yayoi-period "onigiri fossil": What was found at the Sugitani Chanobatake site in November 1987 was a chimaki-shaped lump of carbonized rice. It may have been a rice ball, although some researchers think it was cooked rice placed in a basket that later carbonized.
• November 18 is Onigiri Day, too: In 2015, Nakanoto Town also designated November 18 as Onigiri Day, after the month the fossil was found.
• Rations on the battlefield: Because they were easy to carry and quick to eat, rice balls were long used as portable rations in war.

How Onigiri Became What It Is Today

It took a long time for onigiri to take on its modern form.

• Nori wraps came in the Edo period or later: Rice balls wrapped in nori are thought to have appeared from the Genroku era of the Edo period onward, after nori cultivation spread and square sheets were sold as "Asakusa nori."
• Convenience store innovation: In 1978, packaging that kept the nori separate from the rice with a film, so it stayed crisp, appeared at convenience stores, and after further improvements it became the style we know today.

Fun Facts About Onigiri

• "Onigiri" vs. "Omusubi": There are various theories about the two names. One says "omusubi" comes from "musuhi," the divine power of creation, and another says preferences differ by region.
• Why triangles? One theory holds that onigiri are shaped into triangles to resemble mountains, which were believed to be home to gods.
• Why salt? Rubbing salt on your hands before shaping rice is said to be not only for flavor but also to help the rice keep better.
• Starch in cooled rice: When cooked rice cools, part of its starch is known to change into less digestible "resistant starch."
• "Onigiri" going global: Along with the spread of Japanese food, onigiri is growing in popularity overseas, with specialty shops appearing in various countries.

Tips for Enjoying Onigiri Day

• Try shaping an onigiri with your own hands.
• Try a new filling or a regional specialty.
• Ask family or coworkers about their favorite onigiri fillings.
• Look up where your rice comes from and the history of onigiri.

2,000 Years of Food History in the Palm of Your Hand

June 18 is a day to appreciate the long history of the humble onigiri. From a lump of carbonized Yayoi-period rice to nori-wrapped rice balls in the Edo period and today's convenience store onigiri, it has changed shape while supporting everyday life in Japan. For lunch today, why not slowly enjoy an onigiri with your favorite filling?