Right Fourth File Rook

In shogi, Right Fourth File Rook (右四間飛車 migi shikenbisha) is a Static Rook opening in which the rook (飛) is positioned on the fourth file if played by Black (先手 sente) or the sixth file if played by White (後手 gote).

Typically, Right Fourth File Rook develops the right silver into a Reclining Silver (腰掛け銀) attacking structure.

Another Double Static Rook game includes playing Right Fourth File Rook against a Yagura position.

If White is going to attempt Right Fourth File Rook, then after Black advances their central pawn on the fifth move, White should push their rook pawn to the central file forcing White to protect the second with their silver.

After this, White starts developing the Right Fourth File Rook structure by advancing their sixth file pawn (that is, their pawn that is the fourth file from the right side of their board). White aims to move their right silver to the central file through the sixth file and their rook to the sixth file while Black continues building their Yagura position.

A Right Fourth File Rook strategy may be played against a Ranging Rook position such as Fourth File Rook. In a Right Fourth File Rook vs Fourth File Rook game, each player's rook will be directly opposing each other on the fourth file supported by attacking silvers. Below shows an example of Black's Right Fourth File Rook against White's Fourth File Rook.

1. P-7f P-3d, 2. P-2f P-4d, 3. S-4h R-4b. The first six moves are standard Static Rook vs Fourth File Rook piece development. (See: Left Silver-5g Rapid Attack vs Fourth File Rook for explication.)

4. P-4f. The Right Fourth File Rook opening starts by advancing Black's fourth file pawn. This allows an opening for the left silver to pass through the front line of pawns.

...
Wikipedia