Anaguma castle

The Anaguma or Bear In The Hole (穴熊 anaguma, lit. "hole-bear") is a castle used in shogi. (An anaguma is a Japanese badger.) It is commonly used in professional shogi.

This castle can be executed on either side of the board. A player utilizing the Ranging Rook strategy uses a Ranging Rook Anaguma^[] (振り飛車穴熊 furibisha anaguma) on the right side while a player employing the Static Rook strategy builds a Static Rook Anaguma (居飛車穴熊 ibisha anaguma) on the left side. The end-result will place the king in the corner square where the lance started, defended by two gold generals and one silver. This way, the King cannot be easily checked by a knight or a ranging piece.

Other than the Static Rook and Ranging Rook classification, Anaguma castles can be categorized depending upon which piece cover the square at the ear of the king. When the king is positioned at the corner square, if there were only the knight and the lance with no generals, there would be a hole diagonally in front of the king – the 88 (Black) or 22 (White) square for Ranging Rook Anagumas and the 28 (Black) or 82 (White) squares for Static Rook Anagumas. This square is called the diagonal hole. The piece that covers the diagonal hole names the castle. Thus, a Silver Anaguma has a silver positioned on this square whereas a Gold Anaguma uses a gold for this purpose (with the silver on 79 instead of the gold). (Although possible, Bishop and Rook Anagumas are rare.)

One suggested strategy for a rook-side castle is:

Now for silver anaguma:

Or gold anaguma:

When building a left side Anaguma (with a static rook opening), the bishop is moved out of the way of the king, and the 7th file pawn is moved to make space for the bishop, which may be moved elsewhere later.

It's also possible for a gold to be positioned at 67 instead of 78.

Please see HIDETCHI's Shogi Exercises series.

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