tsume shogi time

solve this with play.mogproject.com

find mate

Just move the rook on 2b to the left, 3b, and promote to a dragon.

do you even play shogi?

Yes, the position above can be used using regular chess pieces. Additional pieces like the "lance" when is like a rook but can only go forward and gold and silver pieces are not on the board, and they are not used as an additional piece which you can "drop". Dropping is the ability to add pieces to the board. Here is what it would look like with regular chess pieces.

One restriction above that is not shown is that the queen cannot go multiple squares like a rook in shogi. The piece is actually a promoted bishop which is allowed one square up and down, and left and right. We can use a queen in this case though for this puzzle since the king can only go one square.

Now, we could take the rook with the pawn. Then we could promote to a queen and in normal chess, this would be mate. However, in shogi, you can drop pieces. So, any piece can be dropped to block. This means another move has to be made to capture the dropped piece.

The dropped piece would be on g8. For example let's use a knight:

However, in shogi, you cannot attack diagonally. So, this solution wouldn't work.

We can do the same with the solution I posted earlier. You don't need to use the pawn. The dropped piece would now be on g7 to block the diagonal. The rook would promote to what is called the dragon and does the inverse of the promoted bishop. It can move like a bishop one square. So it is attacking the g8 square. There is also a third solution by moving the rook back one square and promoting to a dragon. Again a piece would be dropped on g7.

@lethemovesmoveyou i see the relationship but shogi is a 9x9 board whereas international chess is an 8x8 board get where i'm going here?

The puzzle doesn't matter in this case, it involved 3x4 squares to solve. I am not trying to say we should play shogi on an 8x8 board. I was talking about the puzzle and the solution. The solution they show on the site is not entirely accurate because you can drop a piece to defend the king.

In tsumeshogi, it doesn't count  if the sole purpose of interposing a piece is to delay the mate. The problem as given is thus considered mate-in-1. If blocking with a piece (moved or dropped) is actually useful, then it counts as part of the solution.

I agree in a regular chess context, but in shogi you either have pieces on the board, or your opponent has 1 or more of your pieces and/or you have 1 or more of their pieces. 

In shogi, delaying mate is a vital part of the game. That is what makes it vastly different than regular chess. It becomes a race. You can try to mate with 6 pieces being dropped for example. If it doesn't work, then your opponent has exhausted your dropped pieces and survived. Now they get to drop pieces. If you took any while playing then you can drop those. It goes back and forth until the player who has enough pieces secures the mate. 

I will see if I can find an example professional game to illustrate this, but I won't be able to display it fully on this site. 

I found a video. Go to 4:12. You will see he is explaining how to solve with a bishop, the other side has the rest of the pieces, and you can clearly see delaying mate is a legitimate defense.

"Delay" in context of tsumeshogi is not useful, if you can take the blocking piece regardless and without consequence. 

Delaying in the context of an actual game, not allowing your opponent to mate you in their current sequence of attack, is an entirely different matter.

Nothing in the linked video supports your claim.

Then why do the puzzle? If it is truly a mate, and your argument is to not drop a piece, then why make any moves? See how stupid this gets? 

You should play out the position fully to show the mate. In a real game, it might be different. The other person could resign. He also promotes the bishop to a horse to finalize the mate. 

The video does support my claim. It's not just my claim, it is how the Japanese play it (in Kyoto at least where they taught me it.)

You do not play absolutely pointless moves, like drop 3 pawns in a row to block a dragon that just mows them down in line to your king, when you have no other defense. The defending side obviously can play other moves to make the mate at least somewhat difficult.

Name the move in the video, to which you refer.

There were 2 moves, which are you talking about?

If there are 2 that you mean, name them both.

I have the video linked, and he explains the bishop moves. He shows what happens if you place the bishop on different squares. He also promotes his bishop to a horse. 

Now it is for you to prove dropping a piece to delay mate is not valid.

B-33 is the correct move for tsume. Nobody can contest that. However, we're talking about the defensive side.

K-12 is the king side's move. This is not a normal move, not interposing a piece. This at least gives a chance to run away, if it doesn't get married immediately, so this is a fine move.

He shows B-55 as an incorrect variation. The drop P-44 stops the mate and is therefore useful. Making useful drops is totally fine. The key is that you don't drop, if it does nothing but waste time.

Making a drop to stop mate is perfectly good and correct. Making a pointless drop to delay mate is unsportsmanlike, and I won't play against such people.

Even if dropping pieces was not supposed to be used in solving tsume problems, then the solution has two answers still. The rook could move down a square in the OP puzzle and promote to a dragon. It doesn't have to go sideways to the left.