Katsuobushi (鰹節) is the Japanese name for a preparation of dried and smoked bonito (skipjack tuna). Katsuobushi is the main ingredient in dashi, a broth that forms the basis of many soups (such as miso soup) and sauces (e.g., soba no tsukejiru) in Japanese cuisine. It is today typically found in bags of small pink-brown shavings, looking somewhat like cedar shavings used for caged pet litter, or the shavings of a plain wooden pencil. Traditionally large chunks of katsuobushi were kept at hand and shaved when needed with an instrument similar to a plane turned upside down, but in the desire for convenience this form of the food has nearly disappeared. Katsuobushi, however, retains its status as one of the primary ingredients in Japanese cooking today.
Popular uses of katsuobushi include stuffing for rice balls (onigiri), seasoning for cold tofu along with grated ginger and green onions, topping for rice (called furikake), and sprinkling with sesame seeds and chopped nori atop cold soba noodles (zarusoba), as well as its primary use in dashi and other prepared foods.