National Dashi Day – October 15, 2026

History of National Dashi Day

Dashi, a staple in Japanese cuisine, traces its origins back over 800 years to the early Heian period. This delicate broth was first crafted by simmering kombu (kelp) and dried fish to extract a subtle umami flavor that became essential in Japanese cooking. The creation of dashi marked the beginning of Japan’s focus on simple, ingredient-driven cuisine, where natural flavors were highlighted.

During the Edo period (1603-1868), descriptions of dashi began to appear in various literature and Japanese cookbooks. It was during this time in the Kansai region (Kyoto & Osaka) that awase dash— a combination of kombu and katsuobushi (dried bonito flakes)— became popular and gradually spread to the Tokyo area (formerly Edo), where dried sardines or dried bonito were traditionally used to make dashi. This blend of kombu and katsuobushi offered a more complex umami profile and was incorporated into traditional dishes like miso soup, nimono (simmered dishes), and noodle broths. However, different regions of Japan have used other types of fish with kombu to make awase dashi. In Kyushu, for example, ago (flying fish) is commonly used, imparting a clean, refined flavor characteristic of the region’s dashi.

Regional differences in dashi preparation are often attributed to water hardness, with Kansai’s soft water allowing kombu’s delicate flavors to shine and Kanto’s harder water resulting in a stronger dashi made with more katsuobushi. However, beyond water hardness, other factors played a significant role. The development of domestic trade routes, particularly the Kitamaebune shipping route, facilitated the transport of kombu from Hokkaido to Kansai. Regional taste preferences have also influenced dashi: Kansai traditionally favors lighter, more refined flavors, while Kanto is known for stronger, richer tastes. 

The unique flavor profile of dashi was formally recognized in 1908, when Japanese researcher Kikunae Ikeda identified glutamate, extracted from kombu (kelp), as the key component responsible for dashi’s distinct taste. He coined the term “umami”, which became known as the fifth basic taste alongside sweet, sour, salty, and bitter. The discovery of umami, directly associated with dashi, revolutionized the understanding of flavor in both Japanese and global cuisines. 

As Japan industrialized in the 20th century, instant dashi products became widely available, making it easier for home cooks to replicate the rich flavors of traditional dashi. 

Today, dashi remains a symbol of Japanese culinary heritage, cherished for its simplicity and versatility. As Kayanoya marks National Dashi Day, we celebrate the profound impact this humble broth has had on Japanese cuisine. In Kyushu, a key regional variation of dashi includes “ago” (flying fish), which is dried and used as a primary ingredient for its clean, refined flavor. This tradition is honored through the annual “Ago Festival” in Fukuoka, held during the peak season for flying fish. The festival draws large crowds each year, where visitors enjoy freshly caught, charcoal-grilled flying fish and other dashi-based dishes.