Christmas is gone over. 

Today is December 25th, Christmas Day.
But it seems like [or: But it's as if] Christmas is already gone within finished yesterday!
Until yesterday, everything in the city was Christmassy.
Cakes and fried chickens [what you wrote isn't wrong, but makes it sound like only <em>whole birds</em> were sold] are were sold everywhere,

all wrapping paper was had Christmas patterns, and Christmas songs could be heard in every shops.
Today, the Christmas mood is has completely changed to a New Year mood.
Supermarkets sells many kinds of <em>Osechi</em> (a traditional Japanese New Year foods) and rice cakes. 

Santa Clauses all around the city are have gone somewhere elsewhere.
Unsold Chrismas cakes are pushed at to the ends of shelves.
Most Japanese eat Christmas dinner (in most cases they are fried chicken) on Christmas Eve.
But... Hey everyone, today is the actual day of Christmas Day is actually today!