Ōmisoka is a Japanese traditional celebration on the last day of the year.
Just like New Year's Eve, Ōmisoka is celebrated as the beginning of a new year with new possibilities, but their celebrations are a little different. Japanese New Year takes place on the last day of the year (December 31st). In preparation for a new year and a clean slate people purify their homes and remove last year's clutter by cleaning from top to bottom.
Traditionally, important activities for the concluding year are completed in order to start the new year fresh, such as house cleaning (osoji: big cleaning), repaying debts, purification (such as driving out evil spirits and bad luck), and bathing so the final hours of the year could be spent relaxing.
Recently, families and friends often gather for parties, including the viewing of the over four-hour K┼ìhaku Uta Gassen (þ┤àþÖ¢µ¡îÕÉêµêª, "Red/White Singing Battle") on NHK, or more recently to watch large mixed martial arts cards. This custom has its roots in the ancient Japanese culture surrounding toshigamisama (µ¡│þÑ×µºÿ - the guardian deity of the New Year and of people's homes), which revolved around the practice of showing reverence toward the gods of the current and upcoming years.
About an hour before the New Year, people often gather together for one last time in the old year to have a bowl of toshikoshi soba or toshikoshi udon 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.
source: Wikipedia.org
At midnight, many visit a shrine or temple for Hatsumōde, or the first shrine/temple visit of the year. Throughout Japan, Shinto shrines (house to Shinto deities) prepare amazake (rice drink) to pass out to crowds that gather as midnight approaches.
Most Buddhist temples have a large bonshō (Buddhist bell) that is struck once for each of the 108 earthly temptations believed to cause human suffering.
This celebration is the equivalent of New Year's Eve in the Western world, and coincides with Saint Sylvester's Day celebrated by some Western Christian churches.
Traditional sayings differ in relation to the time people greet each other