Higashiyoka-higata is a tidal mudflat at the mouths of Honshoe River and Hattae River on the north shore of the innermost section of Ariake Bay. The Site is internationally important in the life cycle of migratory waterbirds, acting as a stopover and a wintering site. About 7,000 migratory shorebirds are recorded from autumn to spring, including over 1% of the flyway populations of the grey plover (Pluvialis squatarola). The Site also support globally threatened waterbirds, such as the critically endangered spoon-billed sandpiper (Eurynorhynchus pygmeus), the endangered black-faced spoonbill (Platalea minor), and the vulnerable far eastern curlew (Numenius madagascariensis) and Saunders’s gull (Chroicocephalus saundersi). More than 1% of the flyway population of Saunders’s gull occur at the Site. A rich biodiversity can be found on the mudflat, including fish, benthos, and halophytes, due to the warm climate, large tidal variation, and shoals which facilitate sediment deposition. Over the years, the extensive mudflats around the Ariake Bay have been subjected to land reclamation and the construction of dykes. As a result, Higashiyoka-higata, together with the two other coastal Ramsar Sites in Ariake Bay, Arao-higata and Hizen Kashima-higata, has an increasingly important role in biodiversity conservation in the Bay. The Higashiyoka-higata mudflats are also locally important as a fishing site and for supporting local cultural practices.