Kimura Joseki.

Static rook, the Bishop Exchange · no named castle (each king beside a gold and a silver) · 木村定跡 Kimura jōseki

The idea

Kimura Yoshio, the first Meijin of the merit era, published this line of the Reclining Silver; ja.wikipedia says he worked it out after losing his title to Tsukada Masao, against the Reclining Silver of the younger players. Both sides build the same position, the old form with the right gold on 5h (5b for White): silvers on 5f and 5d, knights jumped, edge pawns pushed.

When both kings then go into the corner, Black’s to 8h and White’s to 2b, Black attacks with the pawn to 4e, and every pawn sacrifice after it has a job.

The pawn to 3e prepares the knight’s jump; the pawn to 7e goes for the head of White’s knight on 7c, and White spends a bishop drop guarding it; the pawns to 1e and 1c open the edge, and the knight lands on 2e; at the end the rook is given up.

The sources follow it to the position where White resigns, 73 moves from the start: ja.wikipedia and en.wikipedia give the same moves, and a third source plays two of the pawn sacrifices in another order to the same position. That source gives two reasons Black wins: with White’s king castled, the edge attack bites, and Black can give up the rook without danger to its own king.

It only arises because White moves the king to 2b, which ja.wikipedia calls the losing move.

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 symmetric Reclining Silver, with the right gold on 5h, and move the king to 8h.
• The pawn to 4e, and after White takes it, the pawn to 3e: the 4th and 3rd files open for the knight.
• The pawns to 7e and 1e, then the exchange on the 2nd file.
• A pawn dropped on 1c, the knight to 2e and the pawn taking on 3d: the edge and the 3rd file.
• The knight promoting on 3c, the rook to 2d with check and a bishop dropped on 1a, then the rook given up to finish.

What to watch for

• The knight promotes on 3c before the pawn does. The knight leaving 2e is what opens the 2nd file, so that the rook arrives on 2d with check.
• If White takes the pawn on 3e instead of moving the silver, the knight jumps to 4e.
• If White answers the pawn to 4e with the pawn to 6e instead of taking it, a bishop dropped on 4f follows; ja.wikipedia and one other source both call Black well placed.
• White’s king on 2b is the condition. The attack works because the king has gone into the corner.

What it is played against

Do not move the king to 2b. ja.wikipedia calls it the losing move and gives the pawn to 6e instead, attacking first, with a line in which White comes out better (after a blog it cites); Black’s king to 8h is dubious for the same reason, and the line is no longer seen.

Masuda Kōzō’s attack, the pawn to 4e one move earlier from the symmetric position, and later the Tomioka line took its place.