Static Rook (居飛車 ibisha) openings is one of two major opening strategies in shogi. In the opening, the major piece of the rook fights from its starting position on the right side of the board (the 2nd file for Black, Sente, and the 8th file for White, Gote). In contrast, the other major opening deploys the rook to the center or left half of the board in the opening, and is known as Ranging Rook or Swinging Rook (振り飛車 furibisha).
Summary
Compared with Ranging Rook, leaving the rook in its starting position on the 2nd file (8th file for Gote), or in that general area on the right side, can be a more natural idea for a strategy. Although the rook does move in strategies where it's placed on the 3rd file (7th for Gote), such as with Sleeve Rook, or on the 4th file (6th for Gote), such as with Right Fourth File Rook, these openings are still broadly classified as Static Rook, rather than Ranging. The castles mainly used in Double Static Rook games are Yagura, Gangi, and Left Mino (often seen vs Ranging Rook as well). In games against Ranging Rook, rapid castles, such as boat and elmo, or sturdier castles, such as anaguma and millennium, are often used.
For a time, amateurs shied away from Static Rook, as there are many more jōseki lines to memorize when compared with the Ranging Rook, which almost always used a variant of the Mino Castle. However, entering into the 21st century, Ranging Rook has also seen a greater diversification of tactics, such as with Ranging Rook Bishop Exchange, Ranging Rook counter-attacks, and even the appearance of Double Ranging Rook, which has largely closed the gap between difficulty curves. Further, between professionals, there is less of a distinction between Static Rook and Ranging Rook players, and the number of all-rounders are growing. In recent years, the traditional view of "Static Rook Patterns" and "Ranging Rook Patterns" have been overwritten by the growing popularity of unconventional playstyles, such as right-side king, pulling the rook back to the first rank and moving it to the left-side, and so on.
Double Static Rook
In Double Static Rook games (相居飛車, ai ibisha), it is common for both players to try and keep pace with their opponent as they develop their pieces during the opening, and avoid moves that would result in a disadvantage. The main lines of this kind of game can be categorized into Yagura, Bishop Exchange, Double Wing Attack, and Side Pawn Picker, but there are many variations that these could be sub-divided into. It could be said that there are actually six main lines, if the common Bishop Exchange is categorized separately from the Tempo Loss Bishop Exchange, and the Gangi castle, which has been popular in recent years, was included in its own category. To simplify, examples of the four main lines are as follows.
From any of these positions, a variety of different tactics may develop. In a Double Static Rook opening, there is no clear advantage to Sente nor Gote, and there are strategies that can be adopted by either position.
In Yagura or Bishop Exchange, the silver and gold are lined up vertically to create a strong defense to stop the incoming rook from advancing. When playing with the yagura system it is common to build a yagura castle up on the left side and then move the king into this safer position. On the other hand, Double Wing Attack and Side Pawn Picker largely forego this defense in order to begin a rapid attack, freeing up both rooks to run around in any direction and attack from different locations. To be able to respond to these attacks, the king is normally kept near the center so that the entire camp can be quickly defended, and the Central House formation is often used.
Against Ranging Rook
In games against Ranging Rook, the Static Rook side may choose to stick with a simple castle and immediately initiate a rapid attack or take the time to build up a stronger castle and play a slow game. In the case of a rapid attack, the opening will vary depending on which file the Ranging Rook side has has swung their rook to. In the case of a slow game, the main focus will be less a matter of the attack and more a matter of the castle strength of either side, and the opening will be defined strictly by defensive tactics.