score:10
No, it's is not a public holiday. The only legal public holiday for New Year is January 1st, or 2nd if the 1st is a Sunday. However, like Christmas Eve in the West, it's a very quiet day and many businesses, particularly smaller ones, will be closed, and not just the 31st but often several days before/after as well.
Source: 国民の祝日に関する法律, which is the law that defines public holidays in Japan.
Upvote:2
According to the relevant law, the only public holiday around New Year’s is the 1st of January.
That said, this period, known as the New Year holiday period, is one of the few (beside Golden Week and Obon) when most companies/schools will completely shut down for a couple of days (usually 1st to 3rd; with extended periods often including 31st and maybe an additional buffer day to access a weekend. This is especially true for businesses such as banks that tend to be closed on weekends altogether: it is rather likely for them to post a note outside staying the days when they will close around New Year.
Smaller family-run businesses often decide to close across those the days as New Year’s is a family get-together time but some may be interested in making additional profits from those who want to go out with the families on those days.
If you want to know whether a specific shop will open, you have to ask them directly as it’s not really predictable.
Upvote:4
While the vast majority of offices are closed, December 31st is not a national holiday as noted in Japan Guide.