Why would Japan wait to get the game? That's more of the question.
They do have a holiday on the 23rd of December for the Emperor's birthday (since 1868) but I don't think games sell any more or less around that time. Christmas is a bit more of a romantic holiday and likely not celebrated in the same way that the west does as a religious/massive money spending one. In Japan, people will typically spend the holiday going out with their friends or romantic partners, having parties for the year's end, and whatnot. And businesses close for the New Year.
So it isn't so much of a holiday season like in the west where we have multiple religious holidays.