The Anaguma Castle (穴熊囲い, Anaguma-gakoi) — literally “Bear in the hole” — is the most defensively powerful formation in shogi. When properly constructed, it creates an almost impenetrable fortress in the corner of the board, with the king surrounded on all sides by the board edge and multiple layers of Gold and Silver Generals. It is the castle of choice for players who want maximum king safety above all else.
Anaguma is a fascinating and controversial formation. Its sheer defensive power makes it extremely difficult to attack directly, which has led to both its widespread use and its notoriety in the shogi community as a formation that can make games extremely long and technically demanding.
What Is the Anaguma Castle?
In Anaguma, the king retreats all the way to the corner square — position 9-9 — which is the most protected spot on the board. With the board edge forming walls on two sides (the 9th file and the 9th rank), only the forward and diagonal directions remain exposed. Gold and Silver Generals are then arranged to cover these remaining approaches, creating a fortress with no weak entry points.
The name “bear in the hole” describes exactly what the formation does: the king burrows into the darkest corner of the board like a bear retreating into its den, making it nearly impossible to attack directly.
How to Build the Anaguma Castle — Step by Step
Anaguma takes significantly more moves to build than Mino or Yagura, but the resulting fortress justifies the investment in long games.
- Rook to your preferred ranging position (for Ranging Rook players) — or keep Rook on file 2 (for Static Rook Anaguma).
- King to 7-8 — Begin the king march toward the corner.
- King to 8-8 — Continue toward the corner.
- King to 9-8 — Move the king to the edge file.
- King to 9-9 — Tuck the king into the very corner. This is the defining move of Anaguma.
- Lance to 9-8 — Move the Lance forward to clear space and add another defensive piece to the castle structure.
- Knight to 8-7 or Silver to 8-8 — Add a second defensive layer around the king.
- Gold General(s) to 7-8 and 8-8 — Complete the castle by placing Gold Generals to cover the remaining approach squares.
The result is the king at 9-9, completely enclosed by board edges and a wall of Gold, Silver, and Lance pieces covering every accessible direction.
♟ anaguma
Strengths of the Anaguma Castle
Maximum King Safety
No other castle in shogi provides the same level of king safety as Anaguma. The king in the corner is attacked from the fewest possible directions — only through the 8th and 7th files — and those approaches are blocked by multiple layers of strong pieces. Breaking through an Anaguma castle typically requires a sustained, coordinated attack with significant material investment.
Psychological Pressure
Playing Anaguma creates a specific kind of psychological pressure. Once the castle is built, the Anaguma player can focus almost entirely on attacking, knowing their king is extremely safe. The opponent, meanwhile, must decide whether to attack the fortress directly (costly), build their own strong castle (time-consuming), or try to outmaneuver the Anaguma player in the endgame (difficult).
Endgame Strength
Anaguma excels in the endgame. As pieces are exchanged and the board simplifies, a king in the corner is harder to checkmate than one in a more exposed position. Many games featuring Anaguma are decided by which player can break through the opponent’s castle first — and the Anaguma player usually has more time to execute their attack.
Weaknesses of the Anaguma Castle
Very Slow to Build
Anaguma takes 8–10 dedicated castle moves. This is significantly slower than Mino (5 moves) or Yagura (7–8 moves). During the time spent marching the king to the corner, your opponent can develop attacking pieces, build their own position, and potentially launch an attack before your castle is complete. Anaguma must be built carefully, reading the opponent’s intentions throughout.
Vulnerable to Counter-Anaguma
When both players choose Anaguma — a situation called mutual Anaguma (相穴熊, ai-anaguma) — the game becomes an extremely positional, long-term battle where piece count and precise endgame technique determine the winner. These games can become very complex and require deep calculation.
The Corner Trap
Paradoxically, the king’s safety in Anaguma can become a weakness in some endgame scenarios. Once the castle pieces are stripped away, the king may find itself trapped in the corner with limited escape routes. Learning how to handle this king-in-the-corner endgame is an important advanced skill for Anaguma players.
Who Should Play Anaguma?
Anaguma is not the ideal first castle for absolute beginners — its slow build and long-game requirements demand a level of patience and positional understanding that takes time to develop. However, it is an excellent choice for players who:
- Prefer safety over speed in building their castle
- Enjoy long, strategic battles rather than fast tactical games
- Are comfortable playing without immediate attacking opportunities
- Have already mastered the Mino or Yagura and want to explore a different strategic style
Anaguma in Professional Play
Anaguma has been used at the highest levels of professional shogi in Japan. In the 1980s and 1990s, “Anaguma wars” became famous in professional tournaments, with both players building Anaguma castles and engaging in marathon positional battles. Today, professional players have developed sophisticated techniques for attacking Anaguma, and anti-Anaguma strategies are deeply studied. At the amateur and club level, Anaguma remains an extremely powerful choice.
Practical Tips for Anaguma Players
- Watch your opponent’s build speed. If your opponent is developing fast, consider delaying Anaguma in favor of a faster castle like Mino.
- Secure your Bishop diagonal before marching the king. The long march of the Anaguma king can be disrupted by aggressive Bishop plays. Secure your diagonal first.
- Build your attack simultaneously. Do not spend all your moves on the castle. Develop attacking pieces in parallel so you are ready to attack as soon as the castle is complete.
With Anaguma mastered, explore its most common alternative: 06-4. Silver Crown — The Most Powerful Mino Upgrade, which offers excellent all-around protection in a more balanced build time.
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