I originally intended to set this up after the Natsu basho, as I thought it might help to see what happened in the first basho with six Ozeki. But actually, now is probably better since they're all starting from scratch, as it were - none of them are on a Yokozuna run or in a kadoban situation.
Timewise, I went for the middle ground, 6 to 12 basho. Next, I went for Demotion as the reason for losing an Ozeki, simply because I think that's more likely to happen before another tsunatori. Finally, I went for Kotooshu as the first to leave the rank - nothing personal, he certainly has his brilliant days, but they are few and far between when set against his record over the last couple of years. He also seems more susceptible to injury than the rest, unfortunately.
Anyway, let's see what happens.