Originally posted by ares3
Not a single king- a king and pawn it might be possible.
This one till isn't possible, ares3.
We see that Black hasn't moved his h-pawn, so the only piece he could have moved before being mated is his king. If we try to say that White just moved Nf7#, then Black's previous move must have been either ...Kg8-h8, or Kg7-h8, but neither of these are possible because the white king already covers these squares. We can't even say that it is a stalemate and that Black first moved his king into the corner and only then did White move his king to f8 because that means the white knight is already on f7, which means that ...Kh8 is illegal. But change the white pieces to black, and the black pieces to white, and then we could find a solution; White's king would already be on h8 as he moved his pawn from h6 to h7, and then Black would play Nf7# for the win.