Onigiri
Onigiri are rice balls of round or triangular shape. It is a popular food taken out of on picnics or eating while traveling.
Onigiri originated as a food when refrigerators didn't exist yet. So the Japanese came up with a method to keep the rice fresh longer by filling the center with salty or sour ingredient as natural preservatives.
Onigiri are available from convenience stores, restaurants and supermarkets in Japan. People also make them at home.
Popular fillings are Umeboshi(pickled Japanese plum), Tsuna Mayo (tuna & mayonnaise), Shake(salted salmon), Ikura (salted salmon roe), Tarako (salted cod roe), Mentaiko (salted cod roe spiced with red pepper), Konbu (dried kelp), Takana(takana pickles) and so on. They are wrapped with Nori(a dried seaweed-laver sheet), or sprinkled with sesame seeds and salt.
Yaki Onigiri Grilled Onigiri
Yaki Onigiri are plain rice onigiri that are grilled with soy sauce until golden brown and crunchy.