Kumihama oysters are cultivated by attaching seed oysters to ropes and hanging them on oyster racks made of bamboo and thinned wood on the sea surface. Kumihama Bay is separated from the Sea of Japan by a sandbar, and although it faces the rough Sea of Japan, the waters are calm and there is an abundance of plankton, which is necessary for oyster growth, making it ideal for cultivation. Fishermen also make every effort to improve the quality of Kumihama oysters and maintain their freshness, such as by adjusting the water temperature and changing the depth at which the seed oysters grow.