The rules in this game are identical to chess, except that pawns can now promote to Ninja Guards if desired.

The only new piece to the original orthodox chessmen is the ninja guard.

The Ninja Guard is a color bound piece that can move one or two steps diagonally. It can leap over a diagonally adjacent friendly piece to land exactly 2 squares away (a two-space diagonal leap). It can capture on any square it lands, and additionally it can can capture an enemy piece that is diagonally adjacent by jumping over it. It can capture two pieces that stand immediately adjacent in its path on a diagonal (the first diagonally adjacent to it, and the next, right after) by jumping over the first one and capturing the second piece on the square it lands.

The two squares in the middle can be used as a safety area for the king in certain cases, and instead of castling, the king can be tucked in the rear of the palace. This might be useful when the center is blocked and the opponent has already castled making a wing attack very feasible.

 
VARIANT- Capture the Sceptre In addition to the usual way of winning by checkmate, any side can also win by moving its king to the opponent's rear side of the palace (the squares: d9,e9 for white or d0,e0 for black) without being captured i.e. if the squares are not protected by the opponent's pieces. The reason is that there is a sceptre located at the rear of the palace (on any of the two protruding squares) and if retrieved by the opposing king results in an immediate loss!
So the endgame now will involve additional strategy in trying to prevent your opponent from capturing your sceptre while trying to capture your opponent’ sceptre.
Since the usual rules of stalemate, 3-move repetition apply, the use of the opposition is key here.