Christmasy Wagashi

During Christmas time, we see a lot of western-style Christmas sweets mainly fancy cakes. But not only those.
Recently, even Christmassy Wagashi (traditional Japanese confectionery) can be seen. Wagashi is traditionally served with Matcha at tea ceremony, especially the types made of mochi(sticky rice), adzuki bean paste, and fruits, so originally it is far from Christmasy sweets. Yet, what is the Japanese confectionery’s principle?  it is to place an importance on “season”.
Now December is associated with Christmas even among Japanese. So, why not?