Openings · かまいたち戦法（対四間飛車）
Kamaitachi against Fourth File Rook.
Against a Fourth File Rook, take the fifth file with the pawn, run the right silver out to 6e and float the rook on 5f.
The idea
Against a ranging rook the Kamaitachi becomes a long vertical formation, and one opening guide calls this form the Kamaitachi proper. The fifth-file pawn goes to 5e, the right silver climbs 4h, 5g, 5f and 6e, and the rook swings to the centre and floats up to 5f, where it covers its rank.
The left silver follows to 6f, the right gold comes across to 6h and the bishop goes to 7g. The silver on 6e arrives before White can push the pawn to 6d, so White’s Mino cannot grow, and because Black never pushed the rook pawn, the rook can always swing across to 2f.
The moves come from that one guide, which calls the final position the finished Kamaitachi and shows two of White’s tries from it failing; ja.wikipedia and en.wikipedia describe the same formation in words. The rook ends on the fifth file, but the opening is listed with the static rooks, as Shogi Wars files 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 | Open the bishop’s diagonal. White does the same. |
| 3 | ▲４八銀 3i4h | △４四歩 4c4d | The right silver to 4h. Against the rook pawn push here, the game would go into the 19-move line. White closes its diagonal with the pawn to 4d: a ranging rook. |
| 5 | ▲５六歩 5g5f | △４二飛 8b4b | The centre pawn. White swings the rook to 4b: a Fourth File Rook. |
| 7 | ▲６八玉 5i6h | △９四歩 9c9d | The king starts left, to 6h. White pushes the edge pawn. |
| 9 | ▲９六歩 9g9f | △７二銀 7a7b | Black answers on its edge. White’s right silver to 7b. |
| 11 | ▲７八玉 6h7h | △３二銀 3a3b | The king to 7h. White’s left silver to 3b. |
| 13 | ▲５七銀 4h5g | △４三銀 3b4c | The silver to 5g: the base position for the Kamaitachi. White’s silver to 4c. |
| 15 | ▲５五歩 5f5e | △６二玉 5a6b | The pawn to 5e takes the fifth file. White’s king to 6b. |
| 17 | ▲５六銀 5g5f | △５二金左 4a5b | The silver on to 5f. White’s left gold to 5b. |
| 19 | ▲６五銀 5f6e | △７一玉 6b7a | The silver goes on to 6e, early, so that White cannot push the pawn to 6d and the Mino cannot grow. White’s king to 7a. |
| 21 | ▲５八飛 2h5h | △４五歩 4d4e | The rook to 5h. The source calls the silver on 6e and the rook on the fifth file the core of the Kamaitachi. White takes space with the pawn to 4e. |
| 23 | ▲５六飛 5h5f | △３三角 2b3c | The rook floats up to 5f, where it covers its rank, 4f included. White’s bishop to 3c. |
| 25 | ▲６八銀 7i6h | △４四銀 4c4d | The left silver to 6h. White’s silver to 4d. |
| 27 | ▲５七銀 6h5g | △８二玉 7a8b | That silver on to 5g. White’s king to 8b. |
| 29 | ▲５八金右 4i5h | △２四歩 2c2d | The right gold to 5h. White pushes the 2nd-file pawn. |
| 31 | ▲６八金寄 5h6h | △２五歩 2d2e | The gold steps across to 6h. White’s pawn on to 2e. |
| 33 | ▲７七角 8h7g | △２二飛 4b2b | The bishop to 7g. White swings the rook again, to 2b, to attack on the 2nd file. |
| 35 | ▲６六銀 5g6f | The left silver to 6f: the formation is complete, and the rook can still swing across to 2f. |
The plan once you are set up
- Open the bishop’s diagonal, move the right silver to 4h and push the centre pawn; walk the king to 7h.
- The silver to 5g, then the pawn to 5e and the silver on through 5f to 6e.
- Swing the rook to 5h and float it up to 5f.
- Bring the left silver through 6h and 5g to 6f, the right gold across to 6h, and the bishop to 7g.
What to watch for
- An Ishida. Shogi Wars calls it this opening’s natural enemy: a pawn push backed by the rook’s sideways reach drives the silver on 6e back.
- The rook pawn. Keep it at home: that is what leaves the rook free to swing to 2f. If White moves the king to 8b before pushing the pawn to 4e, the guide swings the rook to 2f when White pushes the 3rd-file pawn, then breaks in the centre with the pawn to 5d.
What it is played against
A Fourth File Rook with a Mino that takes space with the pawn to 4e and the silver on 4d, then swings the rook again to the 2nd file; the guide shows Black better in both of its lines. Shogi Wars names the Ishida as the hard opponent.
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.