Castle

In shogi, a castle (囲い kakoi, literally "enclosure") is a defensive formation consisting of two to four connected generals that guard the king. There are a wide array of castles to choose from, and using a particular castle (or choosing not to castle) is a strategic decision that could make the difference between victory and defeat. The two main factors to consider are the type of opening being played and the direction of the attack. In accordance with the proverb "Keep the king and rook separated", a player using a Swinging Rook strategy (where the rook moves to the left side of the board) will typically castle to the right, while a player using a Static Rook strategy (where the rook stays on the right side) will castle to the left. There are exceptions to this rule, such as central castles. With the recent popularity of rapid attacks, it's not uncommon for even pro shogi players to forego castling entirely, using only a cursory defense as needed.

A position where the king doesn't move is called Sitting King and is used in recent modern openings like Bishop Exchange.

Swinging Rook Castles (Right-side Castles)

These castles are typically employed by a Swinging Rook player. The Mino Castle and its variants are the most commonly employed against a Static Rook strategy, as they are strong on the sides but, in a Double Swinging Rook game, players may opt for a castle which can resist attacks from above, such as the Peerless Golds or Right Yagura. The most known castles are:

vs Static Rook openings

• Mino Castle
• High Mino
• Silver Crown
• Kimura Mino
• Half Mino
• Diamond Mino
• Swinging Rook Anaguma (Furi-Ana), 2-4 generals combinations
• Cozy Castle
• Other

in Double Swinging Rook openings

• Peerless Golds (old Twin Gold, Gold Excelsior)
• Right-side Anaguma
• Right-side Yagura
• Other

Static Rook Castles (Left-side Castles)

These castles are most commonly used by Static Rook players. Yagura is considered a very sturdy castle in a Double Static Rook game, but can be slow to construct. The Boat and elmo castles are quicker castles that allow for a rapid attack against a Swinging Rook strategy, but are not as solid as an Anaguma or Mino.

in Double Static Rook openings

• Crab Castle
• Yagura (Fortress) and its variations
• Gangi
• Other

vs Swinging Rook openings

• Boat Castle
• elmo Castle
• Static Rook Anaguma (Ibi-Ana)
• Leftside Mino
• Silver Crown
• Yonenaga's King
• Millenium Castle
• Other

Central Castles

While not very common due to the difficulty of needing to defend on both sides, some strategies keep the king and defending generals in the center of the board, allowing for a faster attack and guarding against drops within the camp. E.g. Side-Pawn Picker (Double Static) or Takada-Style (Double Ranging). Rarely used in Opposition shogi.

• Central House (Nakazumai)
• Nakahara's Castle (Nakahara's King)
• Duck
• Invincible Castle
• Other

Others

Handicap games use special castles like Silver Tandem and others.