This actually brings an interesting thought to my mind; I've never been able to eat one of these because of just how greasy they look, however when I visited China their KFCs had some of the best chicken(?) I've ever eaten, seemingly because it was baked instead of fried. Zero grease and very crispy. If there were a version of this sandwich like that, I could certainly eat it.
This artwork was uploaded to pixiv on February 22, 2012.
Kentucky Fried Chicken Japan sold the Double Down sandwich under the name, "Chicken Fillet Double" for a limited time only from February 2 to February 22, 2012. On the afternoon of February 22, KFC Japan announced that due to its popularity, sales of the product would be extended through mid-March.
(The recipe was changed to accommodate Japanese taste preferences. The published calories were 588 calories, and the published fat content was 34.1 grams.)