Toshikoshi soba symbolizes crossing from the old year into the new during Japan's New Year's Eve tradition of Ōmisoka.
Toshikoshi soba means “year-crossing soba.” People commonly eat the buckwheat noodles on December 31, often shortly before or around midnight. Their long, thin shape is associated with longevity, while the noodles' easy-to-cut texture can symbolize leaving behind the hardships of the past year.
The custom is connected with Edo-period urban life and has several regional variations. Some families add tempura, green onions, or other toppings, and local recipes differ throughout Japan. There is no single mandatory bowl or preparation.
Toshikoshi soba should not be confused with osechi ryōri, the assortment of auspicious foods eaten during the New Year holiday. Nor is it identical to kagami mochi, a decorative rice-cake offering associated with the New Year season.