Kamaitachi.

Static rook, a surprise opening · none (the king never moves) · かまいたち戦法 kamaitachi senpō

The idea

The Kamaitachi is the system of Suzuki Eishun, an amateur who won the amateur Ōshō title in 1986 and 1987 with it; it is also called the Eishun opening after him. Black opens the bishop’s diagonal, then moves the right silver to 4h instead of pushing the rook pawn, and builds the centre pawn on 5f and the silver on 5g whatever White does.

The pawn on 8g is left without a guard on purpose. If White exchanges rook pawns, Black trades bishops and drops one on 7g, hitting the rook and White’s silver on 2b at once.

In the famous 19-move line White grabs the knight on 8i instead, Black takes back on 2b, takes the knight on 2a with the horse, and drops a knight on 5e, threatening to take on 6c without promoting: check, and a fork of the king and the silver. Both sources that print the line call the end winning for Black.

The name is the sickle-weasel of folklore, which cuts people without their noticing. Few opponents still walk into it: the bishop reply became widely known through the Cheerful Central Rook, where the same drop answers an early rook pawn exchange.

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

• Open the bishop’s diagonal, then the right silver to 4h, the centre pawn to 5f and the silver to 5g. Do not push the rook pawn, and do not guard 8g.
• If White exchanges on 8f, take back with the pawn, then trade bishops on 2b and drop one on 7g.
• If White’s rook promotes on 8i, take on 2b, and after White’s bishop drop on 3c, take the knight on 2a with the horse.
• When White’s bishop takes the lance on 9i, drop a knight on 5e.

What to watch for

• After the horse takes on 2a, White can drop a knight on 7g instead of taking the lance. One note gives the answer, the gold to 7h; the silver dropped on 7h of Suzuki’s original book goes wrong there.
• If White pulls the rook back to 8b instead of promoting, the game is calmer: ja.wikipedia continues with a pawn dropped on 8d and the rook swung across to 8h.
• The form against a ranging rook is different, and has a page of its own.

What it is played against

The answer is not to exchange rook pawns early. If White does exchange, pulling the rook back to 8b instead of taking the knight is the calmer reply. Few players still exchange, since the bishop reply became widely known.

Suzuki Eishun’s other surprise

Tsukutsukuboshi (つくつくぼうし戦法)

Suzuki Eishun had a second surprise opening.

The player pushes the rook pawn as a static rook would, then pushes two more pawns, on his own 6th and 7th files, up to the fifth rank, floats the rook up and swings it sideways across the board into an Ishida. ja.wikipedia compares it to the Twisting Rook, and Shogi Wars describes it as a feint ranging rook and a Twisting Rook added together: it looks like an attack on the bishop’s head until the rook goes the other way.

The name is a pun on 突く, to push a pawn, not the cicada. Suzuki first played it as the stronger player in lance-handicap games, and later in the final of the Asahi Amateur Meijin tournament. The board is ja.wikipedia’s diagram from that game, with Suzuki as White. No source gives the moves, and none says how to meet it.