Ah yes, now I understand what you mean,
shermjack. Sorry, I was slow to catch on. Thanks for your patience, and for your further explanation with the image.
The picture I showed of the Dragon Fanning Deck only showed part of the cards, and I didn't realize you were referring to what is going on with the entire faces. My bad - sorry.
The Dragon Fanning Deck does do something similar with the faces, including a tilted card outline. Here's a picture that shows three face cards:
Basically this lets you fan the faces one way and it shows only normal indices, and you fan the faces the other way and it shows the dragon.
So it is a somewhat similar concept as the Sensu deck, but works differently. The Dragon Fanning Deck is basically a one-way deck, and produces only a fan in one direction. The Sensu deck does indeed take that a step further, because it produces fans in both directions. And it also brings in something new by using the white space to incorporate a rectangular card, which is very clever.
In that regard, yes you're right, the Mechanic Industries deck does do something which the Sensu deck did before it. And I'm not aware of a deck that has done exactly that before the Sensu deck, so it would seem to me that those new and expanded elements are indeed innovations with Sensu, which are similar to the design used by the newer Mechanics deck. Again, my apologies for misunderstanding.
NB: The Dragon Fanning Deck was specifically created for fanning by DP Group Ltd in Japan, and is one of several different fanning decks they made. I'm not 100% sure what year it was made, but it has to be 2012 at the very latest, because there is a
demo video for it that dates back to 2012, and the reviews I found for it all date from around 2013-2015. So of the three decks we're talking about (Dragon Fanning, Sensu, Mechanic's), the Dragon Fanning Deck does seem to be the first, and uses a similar concept, but not in the same way as the Sensu deck, which takes it further. There's more information about the Dragon Fanning Deck here:
https://www.wopc.co.uk/japan/dragon-fanning-deck