Beni-imo (purple sweet potato)

Noguni Sokan, a crew official on a Ryukyuan tribute ship from Noguni in today's Kadena, brought sweet-potato seedlings back from Fuzhou in 1605 and planted them in his village. Gima Shinjo learned the method from him and spread the crop across the islands, where it helped prevent deaths from famine. Kadena still holds a Noguni Sokan festival every autumn, and in 2005, at the 400th anniversary, the town declared sweet potatoes 'Noguni-imo'.

Sweet potato stayed Okinawa's staple into the postwar years. Willcox and colleagues' 2014 review of the traditional Okinawan diet says that over half of daily calories once came from sweet potatoes, and that white rice, bread and noodles have largely replaced them.

In 1986 a Yomitan pastry shop then called Porsche joined the village's revitalisation project and began baking beni-imo tarts. The company took the name Okashi Goten in 2015, and Japanese Wikipedia puts annual tart sales above 10 million. Beni-imo also turns up in nmukuji-andaagii (sweet-potato sata andagi), in purple muuchii, and in Blue Seal's beni-imo ice cream, which joined the line-up after the 2000 Okinawa Summit. Blue Seal lists ube as a separate flavour. Ube is the purple yam that Okinawans also call beniyamaimo, and the name comes from Filipino.