On December 31 of every year, locals and tourists participate in hatsumode, the traditional first temple/shrine visit of the year. A monk rings a bell 108 times during the ceremony to cleanse people of the 108 worldly desires.
Another option is to celebrate at the Yokohama New Year countdown at the port. This lively event features a special light show and fireworks. Countdown cruises around the bay are also available.
More information is here.