Castles · 片矢倉
Half Yagura.
A Yagura with the king and the left gold each one file nearer the centre: king 7h, golds 6h and 6g, silver 7g. Built for games where a bishop can be dropped.
How it goes together
Start from a Gold Yagura and move two pieces one file to the right: the king from 8h to 7h, the left gold from 7h to 6h. The rest is unchanged: the silver on 7g behind the 7f pawn, and the right gold on 6g behind the 6f pawn. The golds now stand on one file, 6g over 6h, and the 6h gold is guarded by the 7g silver and the 6g gold. From 6h it also covers 6i, the square where a bishop dropped behind a Gold Yagura cannot be taken. English sources call it the Incomplete or Half Fortress.
Move by move
Black only, from the start position, with the bishop still on the board. The first ten moves are the Quick Yagura: the king walks to 6h and 7h along the second rank, so the bishop needs just one move, to 7i, to leave its square. Then the bishop goes out to 4f and the left gold steps up to 6h.
Step through the moves, or press play.
Tap a move to jump to it. Arrow keys work once the board has focus.
The bishop has to leave before the gold comes up, because 6h is on its road out: 7i, 6h, 5g, 4f. That is also why the 5f pawn goes early. This is the Fujii-style Quick Yagura (藤井流早囲い): Fujii Takeshi paired the castle with the bishop on 4f, a build ja.wikipedia says only Black can play. Sources count the castle one move quicker than a Gold Yagura; here it takes twelve, like the Yagura page, because one move goes on the 5f pawn that opens the bishop’s road.
What it is good against
Dropped bishops. Every source gives the same reason for the shape: the 6h gold is guarded by the 7g silver and the 6g gold, and it covers 6i, so a bishop dropped behind the castle can be taken. That is why it suits games where both players hold a bishop. Sources also count it a move quicker to build than the Gold Yagura.
Where it breaks
The corner side. The 8g square, diagonally in front of the king, is guarded by the king alone, so the eighth file is weaker than in a Gold Yagura, and the edge is thin. Behind the king 7i is open: with an enemy rook on the bottom rank, a gold or rook dropped on 7i is the danger. Attacks from the side are the third weak point.
When to build it
In games where the bishops come off: ja.wikipedia names the Bishop Exchange as its main home, and shows Amano finishing one in his own game after a bishop trade. In Yagura games Fujii Takeshi paired it with the bishop on 4f, as in the build above. A close relative, the Bonanza castle, leaves the right gold on 5h.
Build it at the board.
The app’s lesson walks the king into a Mino one step at a time, and its review names the castle you were building when a game turned.