Ōmisoka and Toshikoshi-soba/udon

Ōmisoka (大晦日^?), New Year's Eve, is the second-most important day in Japanese tradition because it is the final day of the old year and the eve of New Year's Day, which is the most important day of the year.

Around 11:00 pm on Ōmisoka at home, people often gather for one last time in the old year to have a bowl of toshikoshi-soba (年越しそば) or toshikoshi-udon (年越しうどん) together—a tradition based on people's association of eating the long noodles with “crossing over from one year to the next,” which is the meaning of toshi-koshi. While the noodles are often eaten plain, or with chopped scallions, in some localities people top them with tempura. Traditionally, families make Osechi (おせち) for new year day because cooking during the first 3 days of the new year is considered unlucky. Nowadays, most families buy Osechi or cook ordinary dishes.

At midnight, many visit a shrine or temple for Hatsumōde (初詣).

Another regular feature of Ōmisoka starts at 7:30 pm when public broadcaster NHK airs Kōhaku Uta Gassen ("Red vs. White singing contest"), one of the country's most-watched television programs. Popular singers (and singing groups) split into two teams, women in the red team and men in the white, which then alternate while competing for the audience's heart throughout the evening.

When seeing someone for the last time before the new year, it is conventionally to say 良いお年を (yoi o-toshi wo), "Have a good New Year"; once the new year has started and one sees someone again for the first time, one instead says a greeting such as 明けましておめでとう (akemashite o-medetō) "Happiness on the opening (of a new year)".

Hatsumōde (初詣 hatsumōde^?) is the first shrine visit of the New Year in Japan. Some people visit a Buddhist temple instead.