It is known as either nagaimo (kanji: 長芋; hiragana: ながいも) or yamaimo (kanji: 山芋; hiragana: やまいも) in Japanese, depending on root shape. In Chinese it is known as huái shān (淮山), shān yào (山药), or huái shān yào (淮山药). In Korea it is called ma (hangul: 마; hanja: 麻).
Dioscorea opposita is an exception to the rule that yams must be cooked before consumption (due to harmful substances in the raw state). In Japanese cuisine, it is eaten raw and grated, after only a relatively minimal preparation: the whole tubers are briefly soaked in a vinegar-water solution, to neutralize irritant oxalate crystals found in their skin. The raw vegetable is starchy and bland, mucilaginous when grated, and may be eaten plain as a side dish, or added to noodles.
Dioscorea opposita is used in the Japanese cold noodle dish tororo udon/soba. The grated nagaimo is known as tororo (in Japanese). In tororo udon/soba, the tororo is mixed with other ingredients that typically include tsuyu broth (dashi), wasabi, and green onions. Jinenjo (Dioscorea japonica, also called wild yam) is related variety of Japanese yam that is used as an ingredient in soba noodles.