This item, called コロッケ from the French
croquette, is an unremarkable, common part of Japanese food culture. You can find them sold in most convenience stores and substanitally all supermarkets. (About 80 cents for one in a convenience store, perhaps 60 cents if you buy a five-pack and fry them yourself for dinner.)
KFC is, most definitely, not attempting to sell a newfangled, unhealthy food to the unsuspecting Japanese populance.