english

Duck castle

Kanji
アヒル囲い

Katakana
アヒルがこい

Romaji
Ahiru gakoi

Meaning
Duck

Usage
Static rook

Pros
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Cons
–

Notes

The Ahiru gakoi (Duck Castle) is part of the Duck Opening and is a surprise strategy in shogi. It is called “Duck” because of the shape of the castle constructed, known as the Duck Castle. This opening is characterized by a formation similar to a Double Wing Attack that then transitions into a Twisting Rook-like position. It is usually used when both players play Static Rook (Ibisha), but there is also a variant for when the opponent uses Ranging Rook (Furibisha). Professionals usually avoid this strategy.

The main objective of this opening is to exchange major pieces with the opponent and then reuse them in their playing area, possibly taking advantage of the opportunity to promote them. The Ahiru castle offers good defense against dropped pieces. Theoretically, the player using this opening should have an advantage. If the piece exchange fails, Ahiru seeks to attack the flanks to break through the opponent’s defenses.

Against Ibisha, the opening usually begins with a pawn advance, typical of a Double Wing Opening.

One variation involves advancing the bishop to 97. A pawn protects the bishop’s head while it threatens the opponent’s pawn on 53.

Another variation involves moving the rook to a “floating” position on the sixth rank. This serves to protect the bishop from a potential opponent’s attack.

A common move is the exchange of pawns to gain one in hand.

The Ahiru gakoi is constructed by advancing the two silver generals toward the center, then moving the gold generals outward to form the duck’s legs.

The opening can lead to a rook exchange. The player using the Ahiru usually prefers to trade rooks, as their gakoi is well-protected against a potential rook drop. If the opponent does not exchange, the player will attempt to attack the flanks.