Yagura castle

Yagura or Fortress (矢倉囲い or 櫓囲い yaguragakoi) is a castle used in shogi. It is considered by many to be the strongest defensive position in shogi in Double Static Rook games.[1]

A yagura

A common Yagura structure is the Gold Yagura (金矢倉 kin yagura). It has a strongly protected king; a well-fortified line of pawns; and the bishop, rook, and a pawn all support a later attack by the rook's silver or knight. It is difficult to break down with a frontal assault, though it is weaker from the side. It is typically used against static rook openings that involve advancing the rook's pawn. However, one's opponent may just as easily adopt this defense, giving neither side an advantage.

Yagura is also the name of an opening strategy that uses a Yagura castle (see: Yagura opening).

History

Hon'inbō vs Ōhashi 1618
position after 50 moves
☖ pieces in hand: –
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香桂  角  桂香1
 王金   飛  2
   金 銀 歩 3
歩銀歩歩歩歩  歩4
 歩    歩歩 5
歩 歩歩歩歩  歩6
 歩銀金 銀   7
 玉金   飛  8
香桂角    桂香9
☗ pieces in hand: –

A Yagura castle structure was first formed by Sansa Hon'inbō in 1618 who was playing a Static Rook position (eventually Sleeve Rook) against Sōkei Ōhashi I who was playing a Fourth File Rook position (eventually Third File Rook).[2][3]

In the modern era, Yagura castles are typically used in Static Rook positions against Static Rook opponents (that is, in Double Static Rook games). However, Static Rook positions playing against some Bishop-Exchange Ranging Rook position may also use a Yagura variant after the bishop trade off. Furthermore, Yagura castles constructed on the right side of the board may be used in Double Ranging Rook games.

Gold Yagura Development

There is a good deal of flexibility in the order of moves when building the Yagura defense. A point to keep in mind is that the generals should move diagonally, not directly forward.[1]

While forming the castle, the rook's pawn is often advanced two squares in preparation for a climbing rook assault on the opposing king. Another common preparation is to advance the adjacent silver's pawn square, allowing passage for both the rook's silver and knight. These offensive moves are not properly part of the castle, but the two-square pawn advance must be carried out early if there is to be room for it, and so it is often done while still castling.[1]

In the following three sections are possible typical developments of a Yagura castle in Double Yagura opening games. The first are normal castle development sequences of nine moves. The last section shows the development of a Quick Yagura which is one move faster than usual methods.

However, the specific order of the castle move sequence will vary depending on White's piece development. Moreover, the castle usually isn't built all at once – rather, castle development is interwoven with the development of the attacking pieces. Additionally, moving the king all the way into the castle to the 88 square is not always optimal depending on the state and nature of White's attack.

Classic Yagura

The development of the Gold Yagura castle in the Classic Yagura (旧矢倉) opening is shown below for Black. This is a 9-move sequence that is fairly typical.[4][5]

Classic Yagura
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         1
         2
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         4
         5
  歩歩歩    6
歩歩銀金     7
 玉金角     8
香桂      9
☗ pieces in hand: –
(xiii) K-88

New Yagura

The development of the Gold Yagura castle in the New Yagura (新矢倉) opening for Black is shown below.[6] The New Yagura castle construction differs from the Classic Yagura construction starting from the player's third move.

New Yagura
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         1
         2
         3
         4
         5
  歩歩歩    6
歩歩銀金     7
 玉金角     8
香桂      9
☗ pieces in hand: –
(xiii) K-88

Quick Yagura castle

Quick Yagura castle or Quick Yagura castling or Rapid Yagura castling (矢倉早囲い yagura hayagakoi) is a faster way of forming a Yagura castle than the standard way in that it saves one tempo. It is not a distinct castle but rather a method of castle construction.

Quick Yagura castling will lead to the intermediate position seen in the adjacent diagram. This intermediate position does not occur when a Yagura is built using the slower traditional move sequence.

(The term 早囲い hayagakoi also refers to the Quick castle, which is otherwise known as the Wall castle.)

Attacking Yagura

A common attack against the Yagura defense is to advance the rook's knight directly forward, defended by the rook and with a pawn in hand, to attack the fortifications on either side of the castled king.[1] If the defender has answered a lance's pawn advance on that side, a pawn may be dropped where the edge pawn had been. If the defending silver has moved or is not yet in position, a pawn may be dropped there.

Variants

Although the Gold Yagura castle is very common, there are several variants of Yagura.

Silver Yagura

Silver Yagura
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         1
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         5
  歩歩歩    6
歩歩銀銀     7
 玉金      8
香桂       9
☗ pieces in hand: –

A Silver Yagura (銀矢倉 gin yagura) uses a silver on 67 instead of a gold.[7] This allows for defending of the gold on 78, which is only defended by the king in a Gold Yagura. Silver Yagura allows for greater flexibility with two silvers on rank 7. In a Gold Yagura, if the silver on 77 moves to 76, it is not be able to return 77, and if the gold on 67 moves to 76, it can't move back to 77. Using two silvers on 77 and 67 allows for the same range of defense on 86, 76, 66, and 56 as well as the greater potential of both silvers returning to 77 and 67 after moving up to rank 6. However, by using a second silver for the castle, one gives up the use of the silver for offensive purposes and the side of silver (57) is not defended.

Silver Yagura 2
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         1
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         5
  歩歩歩    6
歩歩金銀     7
 玉銀      8
香桂       9
☗ pieces in hand: –

Another castle which has a different structure may also be called Silver Yagura. It uses a silver on 67 and also on 78 instead of a gold. The gold is then positioned on 77. Like the Silver Yagura above, the silver on 67 defends the 78 square. If your opponent's bishop can be positioned on 68 and they have a gold and silver in hand, the king may be easily mated in this Yagura variant.

Incomplete Yagura

Incomplete Yagura
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         1
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         4
         5
  歩歩     6
歩歩銀金     7
  玉金     8
香桂     9
☗ pieces in hand: –

An Incomplete Yagura or Half Yagura (片矢倉 kata yagura) has the king and the gold on 78 and 68, respectively, instead of the positions 88 and 78 as in the usual Yagura castles. This positioning is meant to protect from the opponent's bishop being dropped onto 69 or 59 (highlighted in diagram) after a bishop exchange as now the gold on 68 is defended by the silver on 77 and the gold on 67 and the gold on 68 can attack 69.[8][7] In a Gold Yagura, the gold on 68 is not defended by any piece besides the king, and it cannot attack a bishop that was dropped on 69. An Incomplete Yagura is also known as Amano Yagura (天野矢倉), named after Edo period shogi master Sōfu Amano.

Right Yagura

Right Yagura
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         1
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    歩歩歩  6
     金銀歩歩7
      金玉 8
       桂香9
☗ pieces in hand: –

A Right Yagura or Right-Hand Yagura (右矢倉 migi yagura) is a Yagura castle built on the right side of the board instead of the traditional left side.

A Right Yagura may be useful in Double Ranging Rook positions since the Yagura structure is strong against attacks from above.

A demerit of Right Yagura is that it requires several moves to create (compared to other Ranging Rook castles like Mino castle).

A Mino castle may transition into a Right Yagura.

Complete Yagura

Complete Yagura
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         1
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         5
  歩歩歩    6
歩歩銀金銀    7
 玉金      8
香桂       9
☗ pieces in hand: –

There several other Yagura variants shown below.

The Complete Yagura (総矢倉 sōyagura) is called complete since it uses four generals instead of the usual three in which the right silver is positioned on the 57 square in Black's castle or the 53 square if White's castle.[7] Since the player's silvers are on the same rank on 57 and 77 (Black's castle), the two silvers are prone to be forked by the opponent's knight (on 65).

The joseki for the Double Complete Yagura can often lead to a repetition draw since both sides are felt to be a zugzwang situation.[10][11] Thus, it may be used purposely in order to strategically switch sides (since Repetition Draw outcomes lead to a new game being immediately replayed but with the player's sides reversed). Nonetheless, it is still possible to play a Double Complete Yagura game without a repeitition draw. The 1976 May 13 Meijin game between Kunio Yonenaga and Makoto Nakahara is an example of such a game.[12]

Square yagura

Square Yagura
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         1
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         4
         5
  歩歩歩    6
歩歩銀銀角    7
 玉金金    8
香桂      9
☗ pieces in hand: –

This Yagura variant is very strong.

Firstly, a bishop is unable to drop to the yellow squares which are possible in a Gold Yagura. Secondly, 57 is protected by the 68 gold. Thirdly, the 76 and 66 squares are not weak points. But, it is dangerous if attacked on the left edge.


Rapid Attack Yagura

Rapid Attack Yagura is characterized by the fact that White (gote) will start the fight following Black's (sente) blocking of the bishop's diagonal. It's said to be an active plan where White wants to avoid a development in which Black takes hold of the initiative. The side playing Yagura aims at building up a position wary of a rival's quick attack. There are a number of variations:

The rapid attack strategy will vary depending on whether in the fifth move Sente goes with P-66 or S-77. For example, both Sitting King Bogin and Right Fourth File Rook are played following P-66, while Central Rook Yagura and Akutsu Rapid Attack Yagura are played following S-77. Yonenaga Rapid Attack Yagura can be played against either.

Other Yagura variants

Yagura Anaguma
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         1
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  歩歩歩    6
歩歩銀金     7
香 金      8
玉桂       9
☗ pieces in hand: –
  • Diamond Yagura or Lozenge Yagura (菱矢倉 hishi yagura)
  • High Silver Yagura or Silver Standing Yagura or (銀立ち矢倉 gintachi yagura)[7]
  • Kikusui Yagura or Floating Chrysanthemum Yagura (菊水矢倉 kikusui yagura)
  • Dented Yagura or Hollow Yagura (へこみ矢倉 or 凹み矢倉 hekomi yagura)
  • Yagura Anaguma (矢倉穴熊)

The High Silver Yagura is used in the King's Head Vanguard Pawn strategy.

Crab castle

Crab
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         1
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  歩 歩    6
歩歩 歩     7
 角金銀金銀   8
香桂 玉     9
☗ pieces in hand: –

When building a Yagura castle, there is a strong intermediate position called the Crab castle (カニ囲い kani gakoi).[1][13] It has the three pawns on the left side advanced to their final Yagura positions, and on rank 8 all four generals are lined up next to the bishop, which is still in its starting position: 角金銀金銀 bishop-gold-silver-gold-silver. The king is moved one square to the left, behind the middle silver.

The crab name comes from the way the king at 69 can only move from side to side (79, 59).

See also

References

  1. 1 2 3 4 5 Fairbairn 1984.
  2. ↑ "本因坊算砂の人物像と囲碁将棋界への技術的功績を再検証する" (PDF). Retrieved 26 October 2017.
  3. ↑ "本因坊算砂 vs. 初代大橋宗桂 その他の棋戦". 将棋DB2. Retrieved 26 October 2017.
  4. ↑ Aono 1983.
  5. ↑ Hosking 1997.
  6. ↑ "About a Yagura castle". kingcrimsondiscipline.blogspot.jp. Retrieved 26 October 2017.
  7. 1 2 3 4 Hosking 1997, p. 47, Part 1, Chapter 8: Castles.
  8. ↑ 柿沼, 昭治 (1979). Shōgi ni tsuyoku naru hon 将棋に強くなる本 [Becoming Strong at Shogi] (in Japanese). 金園社 [Kin-ensha]. p. 29. ISBN 978-4321-55222-6.
  9. ↑ "藤内金吾 vs. 藤川義夫 その他の棋戦". 将棋DB2. Retrieved 26 October 2017.
  10. ↑ 大平 2016, p. 16–17.
  11. ↑ Hodges (1976–1987)
  12. ↑ "米長邦雄 vs. 中原誠 名人戦". 将棋DB2. Retrieved 26 October 2017.
  13. ↑ Hosking 1997, p. 46, Part 1, Chapter 8: Castles.

Bibliography

  • Aono, Teruichi (2009) [First published in 1983]. Better Moves for Better Shogi. Translated by Fairbairn, John (2nd ed.). Ishi Press. ISBN 978-4-87187-999-6.
  • Aono, Teruichi (1983). Guide to shogi openings: Unlock the secrets of joseki 将棋定跡のカギ: 和英 定跡問題集. Translated by Fairbairn, John. 山海堂. ISBN 4-381-00598-8.
  • Fairbairn, John (1984). Shogi for Beginners. Ishi Press. ISBN 978-4-8718-720-10.
  • Hodges, George (ed.) 1976–1987. Shogi Magazine. The Shogi Association.
  • Hosking, Tony (1996). The art of shogi. The Shogi Foundation. ISBN 978-0-95310-890-9.
  • Kaneko, Takashi (2003). Storming the Mino Castle 200. Translated by Sams, Richard. Nekomado. ISBN 978-4905225058.
  • Kitao, Madoka (2012). Edge attack at a glance. Translated by Kawasaki, Tomohide. Nekomado. ISBN 978-4-9052-2502-7.
  • Kitao, Madoka (2014). Ending attack at a glance. Translated by Kawasaki, Tomohide. Nekomado. ISBN 978-4-9052-2513-3.
  • 大平, 武洋 (2016). 矢倉囲いを極める77の手筋. マイナビ出版.


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