Since it's layered with 3 slices of cheese, they're calling it the Mille-Feuille Cheeseburger. A mille-feuille is probably better known as a Napoleon, a flaky, layered pastry. It seems a bit of a stretch to compare the two, but hyperbole I guess. Other than the cheeses, Wendys Mille-Feuille Cheeseburger comes with two beef patties, lettuce, and a brioche bun. It's priced at 920 yen (~$8.60 US).
Also available for the fall are two returning members of the Japan Premium line: the Snow Crab Salad Burger and the Iberico Bacon Mushroom Melt Burger.
The Japan Premium trio is available through October 26, 2014.