What name is given to Japan's traditional New Year's Eve noodle dish eaten for longevity?

Japan’s traditional New Year's Eve noodle dish eaten for longevity is called toshikoshi soba.

Toshikoshi soba means “year-crossing soba.” People commonly eat the buckwheat noodles on New Year's Eve, and their long, unbroken shape is associated with a long life. The noodles can also symbolize letting go of the hardships of the old year because they are easy to cut while eating.

The dish is served in many regional styles, so there is no single mandatory broth or topping. Common versions use a warm dashi-based soup, scallions, tempura, kamaboko, or other ingredients. Families may eat it before or after midnight depending on local and household practice.

Toshikoshi soba is one of several Japanese New Year's food customs. It should not be confused with osechi ryori, the assortment of prepared foods traditionally served during the first days of the new year. The soba specifically belongs to the year-end transition.