Nikon Rumors came up with the above image, which is purportedly from a Nikon ad in Japan. The Japanese letters are believe to translate as “big”.
I don’t think that’s an MF sensor, which seems a little inconsistent with the previous “Big” and “MX format” rumors. Although, those two things could be separate I suppose. If this is legit, it seems like it would be the Nikon 24MP camera that we’ve been hearing about for a while.