For JSTOR, Julia Métraux looked at the popularity of Christmas in 60’s Japan and where it originated:
Anthropologist David W. Plath observed a growing tradition of celebrating Christmas in Japan in the 1960s. Originally introduced by missionaries in the sixteenth century, the holiday and its trappings only really gained traction in the nineteenth century.
“By the 1870s some famous Tokyo stores such as Maruzen and the Meiji-ya were displaying Christmas decorations and were importing Christmas cards and gifts,” Plath noted, and by the 1920s, “Christmas was percolating downward and outward into the lower classes and rural regions.”
If you fancy a more Japanese-style Christmas, you can follow tips from The Japanese Shop and read more about the nation’s yuletide traditions via Kansai Odyssey.