What is the Japanese rice ball often wrapped in nori?

The Japanese rice ball often wrapped in nori is onigiri.

Onigiri is made by shaping cooked rice, usually japonica rice, into a ball, triangle, cylinder, or another compact form. It may be salted or filled with ingredients such as umeboshi pickled plum, salted salmon, kombu, tuna mayonnaise, or fish roe. Nori provides flavor and makes the rice easier to hold without sticky hands, but not every onigiri is wrapped in seaweed.

Rice balls have been portable food in Japan for centuries. Historical references describe related forms such as tonjiki, and the word connected to onigiri appears in the Hitachi Province Gazette dated to 721. Nori became more widely available in sheet form during the Edo period, helping establish the familiar wrapped style.

Onigiri is often sold in Japanese convenience stores, supermarkets, and specialist shops as a practical snack or lunch. It should not be confused with sushi: onigiri normally uses plain or lightly seasoned rice, while sushi rice is seasoned with vinegar, sugar, and salt. Nigirizushi may look similar because it is hand-shaped, but it is a type of sushi, not a rice ball.