up. In the Heian period, rice was made into small rectangular shapes known as tonjiki so that they could be piled onto a plate and easily eaten. At that time, onigiri were called tonjiki and often consumed at outdoor picnic lunches.

The first incarnation of the word onigiri is attested in the Hitachi no Kuni Fudoki (Hitachi Province Gazette), dated to 721 AD. In it,