Openings · 角換わり
Bishop Exchange.
Trade the bishops early, so both sides hold one in hand and every square one could be dropped on has to be watched.
The idea
This is not a system and it is not something you can play alone: the opening is defined by the bishop trade, and in the main line it is WHITE who takes. Your part is to invite it. The bishop steps up to 7g, the silver comes to 8h so the recapture is ready before it is needed, and the golds tidy up the squares a bishop in hand would love.
After the trade both players hold a bishop, and that changes what counts as a weakness: an undefended square in your own camp is now a piece, and both sides spend the next ten moves making sure there are none. The king has not castled at the end of the line below.
The silver on 7g and the gold on 7h are already part of the 兜矢倉 (Helmet Fortress), which is complete once the other gold reaches 5h and the king 6h. The other common home is the 片矢倉 (Half Fortress): the king on 7h with one gold beside it on 6h, the other diagonally in front on 6g, and the silver on 7g.
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 | △８四歩 8c8d | White pushes the rook’s pawn. |
| 3 | ▲２六歩 2g2f | △３二金 4a3b | The gold to 3b. With the bishops about to come off, that square needs covering. |
| 5 | ▲７八金 6i7h | △８五歩 8d8e | And this gold guards the bishop’s head, which is the square everyone in this opening is thinking about. |
| 7 | ▲７七角 8h7g | △３四歩 3c3d | The bishop steps up. Now it can be taken. And this opens White’s bishop onto it. |
| 9 | ▲８八銀 7i8h | △７七角成 2b7g+ | The recapture, prepared a move before it is needed. This is what makes the whole thing safe. White trades. A promoted bishop on 7g cannot stay there, so this is an exchange rather than an invasion. |
| 11 | ▲同銀 8h7g | △４二銀 3a4b | The silver takes it back. Both sides now hold a bishop in hand. |
| 13 | ▲３八銀 3i3h | △７二銀 7a7b | The right silver comes up, ready to go three different ways. And both sides finish tidying the squares a bishop could be dropped on, before either does anything ambitious. |
The plan once you are set up
- Count the drop squares before every move. A bishop in hand punishes a gold that has left home and a silver that has not, and most early mistakes here are one careless move from a fork.
- Then choose an attack. There are three standard ones: the Climbing Silver up the rook’s file, the Rushing Silver to 4f and the Reclining Silver to 5f, and the whole opening turns on which of them the other side has prepared.
- Finish the castle. With the bishops gone, the 兜矢倉 or the 片矢倉 is the natural home here.
- Do not drop your bishop early just to be doing something. A bishop in hand is worth more than a bishop on a square, right up until it wins something.
What to watch for
- The bishop’s head: 7g for you, 3c for them. Almost everything in this opening happens near those two squares.
- A gold moved one square too soon. In a game where both sides hold a bishop, that is not a slow move, it is a lost piece.
- Theory. Professionals keep refining the main lines, so the details change over time; what is above is the durable part, not a repertoire.
What it is played against
Another static rook, and it is the choice of most professionals when they want a fight. Against a ranging rook the bishops usually stay on the board and this opening does not arise.
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.