Openings · 筋違い角
Wrong Diagonal Bishop.
Trade bishops on your second move, drop the bishop on 4e, and take White’s pawn on 3d: a pawn up, with a bishop on diagonals your first one could never use.
The idea
The Wrong Diagonal Bishop is Black’s opening, and it starts as soon as White opens the bishop’s diagonal with 3d. You trade bishops at once and, after White takes back with the silver, drop the bishop on 4e.
A bishop that starts on 8h only reaches squares whose file and rank add up to an even number; 4e adds up to nine, so this bishop works on diagonals the first one never could, which is where the name comes from. From 4e it threatens two things: a horse on 6c, inside White’s camp, and the pawn on 3d. White can stop only one.
White usually stops the horse, most often with the silver to 6b, and you take the pawn. The price is time and the bishop itself. You have spent moves on the trade and the drop, and White keeps a bishop in hand for the rest of the game while yours stands on the board, where it is hard to use.
So you bring it back into your own camp and build around it: in the line below, a Fourth File Rook with the king in a Mino. It is one of the oldest openings in shogi. Among professionals it became almost one man’s opening, Takeichi Saburō’s, and after he retired, he said, only amateurs kept playing it.
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.
Step through the moves, or press play.
Tap a move to jump to it. Arrow keys work once the board has focus.
Every move of the line, with reasons
| # | Black | White | Why |
|---|---|---|---|
| 1 | ▲７六歩 7g7f | △３四歩 3c3d | White opens the diagonal. Without this move the opening does not exist. |
| 3 | ▲２二角成 8h2b+ | △同銀 3a2b | The trade, on Black’s second move. The silver takes back. |
| 5 | ▲４五角 B*4e | △６二銀 7a6b | The drop. From 4e the bishop hits 6c and the pawn on 3d at once. The silver covers 6c, so the bishop cannot make a horse there. |
| 7 | ▲３四角 4e3d | △３二金 4a3b | The pawn on 3d is gone. Black is a pawn up; White has a bishop in hand. The gold covers 4c against a horse there. |
| 9 | ▲６六歩 6g6f | △６四歩 6c6d | The pawn steps aside so the bishop can come home. |
| 11 | ▲８八銀 7i8h | △６三銀 6b6c | The left silver heads for 7g. |
| 13 | ▲７七銀 8h7g | △５四銀 6c5d | White’s silver comes to 5d. |
| 15 | ▲６八飛 2h6h | △４四歩 4c4d | The rook to the fourth file: the Wrong Diagonal Bishop with a Fourth File Rook. |
| 17 | ▲６七角 3d6g | △４五歩 4d4e | The bishop is back in Black’s camp, on 6g. The pawn on 4e, with the silver on 5d behind it. This is the setup Fujii Takeshi recommended for White. |
| 19 | ▲７五歩 7f7e | △３三銀 2b3c | |
| 21 | ▲４八玉 5i4h | △４一玉 5a4a | Black’s king walks right, into the Mino. White’s king walks left, into a Yagura. |
| 23 | ▲３八玉 4h3h | △３一玉 4a3a | |
| 25 | ▲２八玉 3h2h | △２二玉 3a2b | |
| 27 | ▲３八銀 3i3h | △５二金 6a5b | |
| 29 | ▲５八金左 6i5h | △４三金右 5b4c | Black’s Mino is complete: king 2h, silver 3h, golds 5h and 4i. White’s Gold Yagura is complete: king 2b, golds 3b and 4c, silver 3c. White has the bishop in hand, Black the extra pawn. |
| 31 | ▲１六歩 1g1f | △１四歩 1c1d |
The plan once you are set up
- Open the diagonal with 7f. If White answers 3d, trade on 2b at once and, after the silver takes back, drop the bishop on 4e.
- Take whichever target White leaves. Against the silver to 6b, the bishop takes the pawn on 3d.
- Push 6f and bring the bishop home before it is chased. This line puts it on 6g; another sourced line uses 7h.
- Build around it. Here the rook goes to 6h and the king walks to 2h behind a Mino. The other plan in the sources is a Climbing Silver up the second file, where the extra pawn helps the attack.
What to watch for
- If White leaves 4c uncovered after you take on 3d, the bishop takes on 4c and makes a horse. That is why White usually plays the gold to 3b next.
- Your bishop on 3d. A silver on 3c or a pawn on 4e takes its squares. The sources name a dropped bishop with no work as this opening’s main drawback, so bring it home in time.
- White’s bishop in hand. White can drop it into any gap in your camp for the rest of the game, so build with that drop in mind.
- The pawn on 4e with a silver on 5d. That is the setup in this line, and it cramps your bishop on 6g. Fujii Takeshi, who worked it out, put your winning chances against it at about one in ten.
What it is played against
White covers 6c with the silver to 6b, or with the gold to 5b, and then protects 4c with the gold to 3b.
The answer the sources favour is the one in this line: a Reclining Silver on 5d and the pawn pushed to 4e, then a Yagura, playing on with the bishop in hand. A ranging rook player can still swing the rook, but the sources treat that as a forced plan.
White can also drop its own bishop on 6e after the gold to 5b, and the game turns wild with both bishops on the wrong diagonal.
Play it against the bot.
The bot’s search levels, 9 to 12, open from a book that holds two of these openings, the Fourth File Rook and the Yagura; the Mino levels play the openings people play. Either way the review afterwards shows you where the game left the line. Try the line, then try the plan.