Center Vanguard Pawn.

Static rook, against a ranging rook · castles into Boat · ５筋位取り gosuji kuraidori

The idea

The Center Vanguard Pawn takes the square 5e, which Japanese players call the tennōzan, the height that decides the battle, and uses it to cramp the ranging rook. With a pawn on 5e and a silver on 5f behind it, White has less room, and its usual counters are harder to play. Black castles in the Boat first.

In the form the source calls the main one, the right silver goes 4h, 5g, 5f; Black then exchanges the 6th-file pawn and builds two silvers on 6f and 5f, with golds on 6g and 6h. It was one of the standard answers to ranging rooks in the late Shōwa era, and ja.wikipedia calls the slow form Ōyama Yasuharu’s. It answers a Fourth File Rook that has not pushed its own centre pawn.

Both sides’ moves have one source, and the finished shape with golds on 6h and 6g has no name in the sources. ja.wikipedia notes that it is seldom played now.

How it goes together

Both sides’ moves are shown, because this opening is an agreement rather than a system: one player cannot reach it alone, so a one-sided list of moves would be a fiction.

The plan once you are set up

• Build the Boat: king to 7h, right gold to 5h, then the right silver to 5g.
• Push the pawn to 5e and bring the silver to 5f. Leave the 3rd-file pawn at home in this form.
• Push the pawn to 6f and exchange the 6th-file pawn with the pawn to 6e.
• Bring the golds to 6g and 6h and the second silver to 6f.

What to watch for

• White’s pawn to 6d. If White leaves it, take the 6th file too with the pawn to 6e.
• White swinging back to the 3rd file. With the 3rd-file pawn at home, White can push the pawn to 3e and switch to an Ishida; keep the silver to 4f and the pawn to 3f ready.
• White’s rook to 6b. When Black pushes the pawn to 6e, the source calls the rook to 6b White’s strongest reply.
• In the left-silver form below, White’s lance to 1b and rook to 4a meet the attack on 4e; the source says that is why that form went out of use.

What it is played against

A Fourth File Rook with a Mino that does not push its centre pawn.

White pushes the pawn to 6d, builds the High Mino and the Silver Crown, and looks for a counter: swinging back to the 3rd file with the pawn to 3e, the rook to 6b, or exchanging on the 5th file with the pawn to 5d.

With the left silver instead

Left-silver Center Vanguard Pawn (左銀型)

The other form brings the left silver to 5g, the square the Boat’s rapid attacks start from, then pushes the pawn to 5e and stands the silver on 5f, while the right silver stays on 4h.

A Japan Shogi Association column gives this build, and the source of the line above gives both sides from move 1: after the pawn to 3f and the knight to 3g, Black pushes the 4th-file pawn to 4f, aiming at the pawn to 4e. White’s answer, the lance up to 1b and the rook back to 4a, is the position on the board, which the source calls White’s best setup.

It shows the attack on 4e failing against it, and says that is why the left-silver form went out of use. ja.wikipedia, for its part, calls the left-silver form the rapid-attack plan of the two, and its figures from professional games of 1989 to 2010 favour it.