These soba noodles are made with buckwheat flour (soba-ko), wheat flour (komugi-ko), and the special addition of yamaimo (Japanese mountain yam). Yamaimo has a mild nutty flavor with a special slimy-slippery texture that enhances the soba noodles. Yamaimo soba is a specialty product that needs to be experienced firsthand as its texture and flavor are hard to describe.