This is one of the reasons I would like to go to Japan.
When the go for it they go for it. Also with KitKat. Why? Time Out Tokyo has a theory:
"It could have something to do with the fact that it's seen as a good luck charm, because 'Kit-Kat' sounds similar to 'kitto katsu', which means 'you will surely win'."
The latest KitKat novelties are
A KitKat flavored sake
KitKat sushi set:
Early February in specialized shops in Ginza, Tokyo