For me, celebrating Xmas in Japan is a little strange because we Japanese mostly aren't Chrstian. However, Xmas is already a kind of year ending event for Japanese people. They buy beautiful cakes and enjoy parties with friends or families.
When I lived in NZ, people were quiet all through the Christmas day. Fot them, of course it's holly time and they spend the time with holly mind with families. But in Japan, people are enjoying the Xmas events at bars, restaurants, or with their families too. Streets are also decolated beautifully with illumination and Santa Claus designs. In Japanese Xmas, it's not especially related wtih religion.
Now we are about to have Xmas day soon. For me this season means just the ending of a year with fun events.