The Japanese holiday season is inverted compared to the US. Christmas is spent as a partying frenzy and as we approach the New Year things slow down. The days before New Year, we spend cleaning our houses and preparing osechi. Osechi is food that keeps well and tastes OK cold. Cooking a lot of osechi allowed the women (who typically did the cooking in the house) to take a break for a few days during the new year. The idea is to cook up a bunch of osechi, eat your noodles, go to the shrine, ask for good luck, and take a break. During the first few days of the new year, you visit family, eat osechi and basically chill out.
I think this is more efficient than the US form where you wake up drunk and hung over on in the New Year with a fuzzy recollection of a bunch of unrealistic New Years resolutions.
Yesterday, I helped Mizuka clean the house, she did most of the cooking (osechi is a bit of an art) and we had her family over for New Years osechi brunch. I passed out (sober) on the floor cuddling with Bo and slept for 18 hours.