Onigiri , also known as omusubi (お結び), nigirimeshi (握り飯), or rice ball, is a Japanese food made from white rice formed into triangular or cylindrical shapes and often wrapped in nori. Traditionally, an onigiri is filled with pickled ume (umeboshi), salted salmon, katsuobushi, kombu, tarako, mentaiko, takanazuke or any other salty or sour ingredient as a natural preservative. Because it is easily portable and eaten by hand, onigiri has been used as portable food or bento from ancient times to the present day. Originally, it was used as a way to use and store left-over rice, but it later became a regular meal. Many Japanese convenience stores and supermarkets stock their onigiri with various fillings and flavors. It has become so mainstream that it is even served in izakayas and sit-down restaurants. There are even specialized shops which only sell onigiri to take out. Due to the popularity of this trend in Japan, onigiri has become a popular staple in Japanese restaurants worldwide.

Japanese cuisine encompasses the regional and traditional foods of Japan, which have developed through centuries of political, economic, and social changes. The traditional cuisine of Japan is based on rice with miso soup and other dishes with an emphasis on seasonal ingredients. Side dishes often consist of fish, pickled vegetables, and vegetables cooked in broth. Common seafood is often grilled, but it is also sometimes served raw as sashimi or as sushi. Seafood and vegetables are also deep-fried in a light batter, as tempura. Apart from rice, a staple includes noodles, such as soba and udon. Japan also has many simmered dishes, such as fish products in broth called oden, or beef in sukiyaki and nikujaga.