Nagaimo
Dioscorea polystachya or Chinese yam , also called cinnamon-vine, is a species of flowering plant in the yam family. It is sometimes called Chinese potato or by its Korean name ma. It is also called huaishan in Mandarin and wàaih sāan in Cantonese. It is a perennial climbing vine, native to East Asia. The edible tubers are cultivated largely in East Asia and sometimes used in alternative medicine. This species of yam is unique as the tubers can be eaten raw.
Source: Wikipedia