As the name suggests, Oita Prefecture Shiitake (or OSK Shiitake) is a farmers' cooperative specializing in shiitake cultivation, based in Oita Prefecture, Kyushu Island. Founded in 1907, it now brings together more than 4000 members and supports its producers in the marketing of their shiitake and the products made from them. With 48% of national production, Oita is the leading shiitake-producing prefecture in Japan, a status that reflects both the richness of its terroir and the expertise of its growers.