Ichikichi is the local name for a variety of purple sweet potato grown on Tanegashima, one of the Osumi Islands in the Ryukyu archipelago of southern Japan. The precise origins of the variety are unknown, but it is thought to have been brought to Tanegashima around 1698. The island and the sweet potato are so closely linked that the ichikichi was commemorated with a monument built on what is believed to be one of the first parcels of land dedicated to its cultivation.
The ichikichi harvest occurs in autumn, from early October to late November. This variety is considered to be its tastiest about three weeks after harvest, so the ideal period for consumption lasts from late October to early January. The skin of the ichikichi is light brown, and the flesh is purple, lightening to varying degrees based on how it is cooked. It is rich in anthocyanins, and is considered to have many properties beneficial for health.
Traditionally, marketing the ichikichi sweet potato was difficult because of its rapid deterioration, and so it tended to be restricted solely to Tanegashima Island gastronomy. A few decades ago, the variety almost went extinct because of several epidemics that stunted its production. Thank to the efforts of a few small companies, especially confectioners, a handful of local farmers still cultivate the ichikichi. In local cuisine, this variety is steamed, fried as tempura, or baked. In addition to being incorporated into soups and stews, ichikichi is used locally as the basis of the sweet kintsuba. To make kintsuba, the ichikichi are cooked, mashed, and reduced to a soft paste. The paste is combined with sugar, flour, and seaweed, shaped by hand, and steamed.