Via Osaka and Satsuma to Ryukyu
An Okinawa Prefecture source describes trade linking Hokkaido, Satsuma, Ryukyu and Qing China in the late Edo period. Japan's agriculture ministry traces a route for kombu: Kitamaebune ships carried it from Hokkaido to Osaka, then it passed through Satsuma to Ryukyu and onward to Qing China.
Ryukyu was both a place where the kelp arrived and a participant in trade beyond it. Those exchanges across several regions help explain how an ingredient from Hokkaido reached Okinawan kitchens.
Kelp, pork and a simmering pot
Kubu means kelp, while irichi means stir-simmering. Cooks cut rehydrated kombu into strips, stir-fry it with pork belly and other ingredients, then simmer it with pork stock, soy sauce and sugar. The kelp is eaten, not merely used to flavour the broth.
The ingredients and method suggest a meeting between dried kelp and Okinawan pork cookery. A food brought from elsewhere became part of a local way of cooking.
The sources do not identify who invented the dish or when. Trade records help explain how kelp arrived; the recipe shows how people came to eat it.
A dish for celebrations
Kubu irichi also appears at celebrations, including weddings. The agriculture ministry notes the wordplay between kombu and yorokobu, meaning to rejoice. The ingredient carries a festive association as well as flavour.
What people serve on a celebratory day is part of a food tradition. Kubu irichi has a place at those gatherings alongside its familiar ingredients and cooking method.
Where an ingredient comes from is only part of a regional dish's story. How people prepare and serve it matters too. Kelp became Okinawan food through what happened after it arrived.