Hey thanks for the answer. We've poked around a little more by taking a closer look at the episode. To start with, my wife watched almost all of the episodes from seasons 1-4 in Japan as they 1st aired. (Ironically the ones that are missing from collections and we have never seen). When watching this episode we had to laugh and point out that the footage from episode 2, Foie Gras is very slow paced. Right when Chairman Kaga gives the 'Ala cuisine" they just start walking around very slowly and making menus. Really strange and funny to see that...

But anyway.. She said she never saw this episode or the Sakai one that will air tonight. But she thinks she saw most of the Michiba shows.
Now, the closing credits say that this was produced by Fuji in Japan and we sort of agree there because it looks like the same type of production and it has Kaga giving quite a bit of narration (although dubbed in English most of the time). One could say that the closing credits were made by [FLN] when they changed the music to the new "Iron Chef Japan" [FLN] versions, but this one actually gives thanks to the song from "Backdraft" that was in the original and is no longer used by the US broadcasts (due to rights restrictions). And then we have the fact that it says 1998 as the production date. And one of the black and white pictures at the start shows Michiba with Morimoto.
So here is our take on it. It appears to have been produced by Fuji in Japan in 1998. Since my wife only watched from 1993-1996 and never say any compilation type episode like this, we think it was shown at the end of season 6, in 1998, in Japan, originally.
And here's a real whopper that I don't see how we missed when watching last night. The very last thing that Kaga says at the end of this episode "The world you fans long to see now begins with Iron Chef episode 1".... Hahah, really!!!

So that pretty much rules out it being produced by FN or FLN, since they don't play season one.
So, our guess is that the episode should be titled S06SP1. And tonights Sakai one should probably go based on the production date with a similar SP. They do appear to be specials that were broadcast right before a repeat of an older season. So people would know who the legacy chefs were. Now why FLN would show this, I don't know, since tonight episode is certainly not the 1st episode that few have ever seen. According to the programe guide at least. Maybe FLN never noticed that this episode says the next one is the very first? We're just glad they played it as the footage of the season 1 episode 2 and the season 2 episode (cheese) were just wonderful to see and no one in the US has even gotten to see those. Well, except for my wife and any other people who lived in Japan from 1993-1996. Hahah! Another thing is that since the newer versions started to air on [FLN] they have never shown anything but episodes from seasons 6 or 7...
Now if you look up the Wiki entry for Rokusaburo Michiba, that says there was a special episode dedicated to him called "Legend of Michiba" in 1996. And since last nights episode does show those titles "Legend of Michiba", perhaps this was made in 1998 like it said, using footage from the original 1996 version, as a lead in / preview to Michiba right before they did a repeat of season 1 in Japan? Perhaps making it the second version of "Legend Of" which would have made since to air in 1996 when he retired? My wife said that Fuji TV did have a habit of making special episodes to lead in to repeats of older series... So that would once again throw it right back to the end of 1998 (season 6), perhaps making it episode 48, with the Sakai special being episode 49? One of the last episodes that [FLN] played from season 6 was in fact episode 47, Turkey Battle.
So what do you think of our theory? I guess calling the Michiba episode S06SP1 would not mess up the numbering system, and it appears to have been made in 1998, season 6. Let's see what tonight's production date says on the Sakai one to determine the season, and maybe at the end Kaga may say something to indicate why it was made as to what's coming up next (when it was produced)..... Time will tell..