Basic Checkmate Shapes in Shogi: Gold on the Head, Side and Tail
Hiroki Obara · Developer
When you have just learned shogi, you can often give as many checks as you like and still not mate the king. You check, the king runs, and before you know it your pieces in hand are gone. I think the main reason this happens is not knowing the mating shapes.
Mate has fixed shapes with names. In this post I explain the three shapes that use a gold: 頭金 (atama-kin, gold on the head), 腹金 (hara-kin, gold on the side) and 尻金 (shiri-kin, gold on the tail). In Basic tsume shogi tesuji I wrote about the sacrifices that bring the king into a mating shape. Here I stay with the final shapes themselves.
I describe positions in words. Squares are written the Japanese way: 5一 means file 5, rank 1, and rank 1 is the defender’s back rank. Pieces without a label belong to the attacker, the side giving mate; the defender’s pieces are marked “defender’s”. For every position I checked with a program that it mates in one, and that no other gold drop mates.
First, what a gold controls
All three shapes are gold drops, so let us start with the gold’s moves. A gold can move to six squares: forward, left, right, diagonally forward, and straight back. The only squares it cannot reach are the two diagonally behind it.
That missing diagonal backward move is exactly what separates the three shapes. Whether you drop the gold in front of the king, beside it or behind it changes which squares the gold covers and which it leaves open. A shape is mate only when the squares the gold leaves open are blocked by the edge of the board or by another piece.
Gold on the head: for a king on the bottom rank
You drop a gold directly in front of the king, on its “head”. This is the most basic mating shape.
Position 1: Defender’s king on 5一. Attacker’s pawn on 5三. In hand: a gold.
A gold drop on 5二 is mate. The gold on 5二 covers 4一 and 6一 beside the king, and 4二 and 6二 diagonally in front of it. The pawn on 5三 protects the gold, so the king cannot take it. The king is on the bottom rank, so it has no square behind it.
Gold on the head works when the squares behind the king are closed. If the king is on the bottom rank, the edge of the board does that job. The other condition is that the gold you drop is protected by one of your pieces. If it is not, the king takes it and escapes.
Gold on the side: for a king on the edge file
You drop a gold directly beside the king, on its “belly” in Japanese.
Position 2: Defender’s king on 1二. Attacker’s pawn on 1四 and silver on 3三. In hand: a gold.
First, try gold on the head. A gold drop on 1三 gives check, and the pawn on 1四 protects it. But the king steps back to 1一 or 2一 and escapes. The king is not on the bottom rank, so gold on the head leaves the squares behind it open.
The answer is a gold drop on 2二. A gold beside the king covers 1一, 2一 and 2三. The remaining square, 1三, is covered by the pawn on 1四. The silver on 3三 protects the gold on 2二, so the king cannot take it. That is mate.
Gold on the side comes up often when the king is on an edge file. The other side of the king is off the board, so it can only escape one way. The only square the gold cannot cover is the one in front of the king, which is diagonally behind the gold, and if another piece covers that square, it is mate.
Gold on the tail: for a king held from above
You drop a gold directly behind the king, on its “tail”.
Position 3: Defender’s king on 5二. Attacker’s dragon (promoted rook) on 3三 and gold on 6一. In hand: a gold.
Again, try gold on the head first. After a gold drop on 5三, the king escapes to 4一 or takes the gold on 6一. Gold on the side, on 4二 or 6二, also lets the king run to the other side.
The answer is a gold drop on 5一. A gold dropped from behind reaches 5二, where the king is, and 4一 and 6一 beside it. The gold on 6一 and the gold on 5一 protect each other, so the king can take neither. 6二 is covered by the gold on 6一, and 4二 by the dragon’s diagonal move. The squares in front of the king, 4三, 5三 and 6三, are covered by the dragon along the third rank. That is mate.
Gold on the tail works when another piece, such as a dragon or a rook, holds the squares above the king (in front of it, from the defender’s side). A gold dropped behind the king only reaches the king’s own square and the two squares beside it. The squares spreading out in front and to the diagonals have to be left to other pieces.
Choosing between the three
Put side by side, the three look like this.
- Gold on the head: the king is on the bottom rank and cannot go back
- Gold on the side: the king is on an edge file and has escapes on one side only
- Gold on the tail: another piece is holding the squares above the king
In every shape, the squares the gold cannot cover must be blocked by the board’s edge or another piece, and the gold you drop must be protected. When both are true, it is mate.
When I look for a way to mate, I think it helps to start by asking which side of the king is the wall. If the wall is below, try gold on the head first. If it is to the side, gold on the side. If it is above, gold on the tail. In Positions 2 and 3, gold on the head failed because the king ran to the side that had no wall.
Where they appear in real games
In real games the king usually sits inside a castle, surrounded by the defender’s golds and silvers. A board as empty as the positions in this post almost never happens. Even so, gold on the head when the castle is broken and the king is left on the bottom rank, gold on the side for a king that has run to the edge, and gold on the tail after a dragon has closed off the top are all shapes you will see.
I think it is easiest to treat gold on the head as the centre of these shapes, with side and tail as variations of it. Shogi has the proverb “keep the gold for the finish”, meaning keep your golds in hand as long as you can so you have one for this final shape. There are other named mating shapes too, such as 腹銀 (hara-gin), a silver dropped beside the king, and 一間竜 (ikken-ryū), a dragon giving check from one square away.
After the shapes, 3-move tsume
Once you can see shapes that mate in one, the next step is 3-move tsume. Most 3-move problems use the first check to drive the king into one of these shapes and mate on the third move. How to read them is in Tsume shogi for beginners, and how to start with children is in Tsume shogi for kids.
Shogi365 is a tsume shogi app with 1,000 puzzles each of 3-, 5-, 7- and 9-move tsume. Any check can be played, right or wrong, and the defender replies automatically, so you can test on the board which shape you were aiming for. If there is no mate within the move count, it is a failure, and you can retry up to three times. After solving, Review lets you step through the line one move at a time and see which shape gave the final mate.
