Twisting Rook.

Static rook, the Double Wing · castles into Bald Mino · ひねり飛車 hineribisha

The idea

The Twisting Rook starts as a Double Wing and ends as an Ishida: a ranging rook game reached from a static rook opening. Black floats the rook on 2f, and when White opens the bishop’s diagonal, the rook goes to 3f, at the pawn on 3d. White guards it with the gold to 3c, which closes White’s own bishop and leaves the king with one gold beside it.

Then Black opens the bishop’s diagonal; White has to exchange on the 8th file at once, and the pawn to 7e offers a rook trade that the sources say favours Black. After the knight jumps to 7g and a pawn dropped on 8e stops White’s rook, Black’s rook crosses to 7f and the king goes into a Mino on the other side, one with no pawn on its head, the Bald Mino.

The form is said to be old; after the war Masuda Kōzō and others organised its theory, and Shogi Wars notes that it was once called a winning method for Black, until White learned to castle firmly and counterattack. The line is one guide’s, after a book by Chūza Makoto.

Every move from the floating rook to the twist is also in a second source or ja.wikipedia, in places in another order; the six castle moves are the guide’s alone. White’s right silver goes to 7b, which the second source calls the more common today; ja.wikipedia’s diagram has the older 6b.

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

• After the exchange on the 2nd file, float the rook on 2f and bring the right silver to 3h.
• When White opens the bishop’s diagonal, swing the rook to 3f, at the pawn on 3d.
• Push the edge pawns and the pawn to 9f, then open your bishop’s diagonal; after White’s exchange on the 8th file, push the pawn to 7e.
• Jump the knight to 7g and drop a pawn on 8e to stop White’s rook.
• Swing the rook to 7f, then castle: the king to 4h, 3i and 2h.

What to watch for

• The pawn to 9f comes before the knight jump, so that a pawn dropped on 8g can be met later, one source says.
• The rook trade. With White’s gold up on 3c and the king thin, the sources say the trade favours Black; White declines by pulling the rook back to 8b.
• White can avoid the plan by leaving the pawn to 3d out and castling firmly with gold and silver first. Shogi Wars says that answer is why the opening declined.
• The edge-bishop tricks of the older form, the bishop to 9g, work against White’s silver on 6b but not against the silver on 7b with the edge pawn on 9d.

What it is played against

White guards the 3rd-file pawn with the gold, exchanges on the 8th file and then keeps the rook back on 8b, with the pawn to 6d and the silver to 6c. The modern answer is to leave the pawn to 3d out and build a firm castle first, then counterattack.