Corbicula japonica is a species of brackish-water clam in the family Cyrenidae found in estuarine and coastal environments of East Asia, particularly in Japan, Korea, China, and the Russian Far East. The genus name Corbicula derives from Latin meaning “small basket,” referring to the rounded shell shape typical of these clams, while the species epithet japonica means “of Japan,” reflecting the region where the species was first formally described. In Japan the clam is commonly known as shijimi (シジミ) and is a traditional ingredient in Japanese cuisine, especially associated with soups and simple broths.

Corbicula japonica inhabits brackish lakes, estuaries, and river mouths where freshwater mixes with seawater. It lives buried in sandy or muddy sediments and feeds by filtering microscopic algae, bacteria, and organic particles from the surrounding water. The species plays an ecological role in these environments by contributing to water filtration and nutrient cycling. Compared with related freshwater species in the same genus, C. japonica is particularly adapted to fluctuating salinity conditions typical of estuarine habitats.

As a food source, Corbicula japonica is harvested commercially and traditionally gathered in shallow estuarine areas. The clams are most commonly used whole in soups such as shijimi miso soup, where their small size allows them to be cooked and served in the shell. The broth produced during cooking is valued for its savory flavor and mineral content. In addition to soups, the clams may be used in rice dishes, simmered preparations, or preserved products.

Nutritionally, the edible tissues of Corbicula japonica contain high-quality protein, essential amino acids, and minerals including iron, zinc, and magnesium. The clam is also known for relatively high concentrations of certain bioactive compounds, particularly ornithine, an amino acid involved in the urea cycle that has been studied for its role in ammonia detoxification and liver metabolism. Other constituents include taurine, glycogen, and small amounts of omega-3 fatty acids, which contribute to the nutritional profile of the clam.