Spread Golds.

How it goes together

The king takes one step straight up, to 5h, the Central House square. The left gold goes up to 7h and the right gold up and across to 3h, so the two golds stand two files from the king on either side; the name says they are opened out. Both silvers stay at home on 7i and 3i, each guarding the gold in front of it, and the rook on 2h also guards the 3h gold. 6h and 4h, beside the king, are each covered by the king, a gold and a silver. The three squares behind the king, 6i, 5i and 4i, are covered by the king alone.

Move by move

Black only, from the start, in the order of ja.wikipedia’s sentence: the left gold, the right gold, then the king. No teaching site has a page for this castle, so every source is a Wikipedia article.

Three moves. Add a silver on 4h and it is the usual Central House. The reading is disputed: the castle’s own Wikipedia article reads 金開き kinhiraki, the Japanese glossary of shogi terms kinbiraki; this site follows the article.

What it is good against

Few moves and no corner. As a kind of Central House it values balance over hardness and is built to meet rook and bishop drops (ja.wikipedia, citing the Japan Shogi Association’s guidebook). The stronger player in handicap games uses the same shape (ja.wikipedia).

Where it breaks

The king’s head. The Central House is considered weak to an attack from above the king (ja.wikipedia), and in this form neither silver has come up to help. ja.wikipedia also says it is seldom seen against a ranging rook.

When to build it

Double static rook games: ja.wikipedia says it arises often in the Aono line (青野流) of the Side Pawn Capture, which is Black’s. Older surprise openings build it too, and a 1952 book of surprise openings names it in its title beside the Demon Killer and the Ishida. Katō Jirō once used the name for the Duck; this site gives it to this shape, as ja.wikipedia’s article on the name does.