The rice balls are stuffed with various fillings and typically wrapped in seaweed. It's an everyday dish epitomising "washoku" — the traditional Japanese cuisine designated a UNESCO Intangible Cultural Heritage a decade ago. Onigiri is "fast food, slow food and soul food," says Yusuke Nakamura, who heads the Onigiri Society, a trade group in Tokyo. Fast because you can find it even at convenience stores, slow because it uses ingredients from the sea and mountains, he said—and soul food because it's often made and consumed among family and friends. No tools are needed, just gently cupped hands.