The Japanese name for New Year's Eve, observed on December 31, is Ōmisoka.
Ōmisoka is the final day of the Japanese year and is one of Japan's most important annual observances. Families commonly prepare for the new year, clean homes, settle obligations, and eat toshikoshi soba, noodles whose name means “year-crossing soba.” Buddhist temples ring their bells in the jōya no kane ceremony, traditionally 108 times.
The following New Year's period is Shōgatsu, not Ōmisoka. That distinction matters: Ōmisoka refers specifically to December 31, while Shōgatsu covers the New Year's celebration and the first days of January. Japan adopted the Gregorian calendar for civil use in 1873, so modern Ōmisoka occurs on December 31 rather than according to the former lunisolar calendar.