When it comes to Christmas dinner, most of us have a pretty clear idea of what to expect - turkey with all the trimmings, lashings of gravy and more cheese than we can handle.
The unusual Christmas tradition began in the 1970s, when the manager of the first Japanese branch, Takeshi Okawara, had the festive idea in a dream.
He thought it would be great if the American chain offered its Japanese customers a 'party barrel' for the holidays.
Apparently, he got the idea after overhearing foreign customers complaining that they'd be bereft without a turkey at Christmas, as the holiday isn't traditionally celebrated in Japan.
This is because only a very small fraction of the Japanese population is Christian (around one percent), although in recent years, more people have been marking the holiday in some way.
While Okawara wasn't planning to change up the KFC menu to offer turkey, he concluded that festive chicken would be a great alternative and got to work on his party barrel.
This eventually resulted in what was known as Kurisumasu ni wa Kentakkii - or Kentucky for Christmas - and it proved to be an instant hit.
The party barrel went down a storm with people in Japan because they were apparently longing to get in on the Christmas action, according to Joonas Rokka, an associate professor of marketing at Emlyon Business School in France.
He told the BBC: "It filled a void.
"There was no tradition of Christmas in Japan, and so KFC came in and said, this is what you should do on Christmas."
The fast food giant now advertises the festive barrels as very much a family activity, showing pictures of happy families crowding around theirs.
They don't just contain chicken and its many forms either, and now the party barrels contain cake and wine too.
Back in 2016, there were a number of festive packages available including a box of chicken for 3,780 yen ($28/£23), or you could bag yourself a 'premium' whole chicken and sides for 5,800 yen ($43/£36).
Naturally, these are promoted by Colonel Sanders in a Santa suit.
However, while the people in Japan can't get enough of KFC at Christmas, it's been speculated that the tradition is unlikely to take off elsewhere.
In fact, Kevin Gillespie, a KFC chef in the chain's home state of Georgia, said he'd be pretty angry if someone suggested KFC at Christmas.
"KFC on Christmas. It's one of the strangest things I've heard," he said. "If you brought a bucket of fried chicken to Christmas dinner, honestly, I'd be mad at you."
Professor Rokka said that this unusual festive tradition is ultimately a byproduct of globalisation.
"This is another sign of globalisation, where consumer rituals spread to other countries and often get translated in different ways," he said.
"It's not abnormal now to have an Ikea store everywhere in the world. This KFC for Christmas is just taking our consumerism and turning it into a holiday."
To put the scale of KFC at Christmas's popularity into context, the chain see its Japanese profits skyrocket in December and it's estimated that 3.6 million Japanese families have some finger-lickin' goodness on the big day itself.