Castles · elmo囲い
Elmo.
A Boat castle with the gold moved under the king to 7i and the left silver up on 6h. Named after the program elmo, and now a common castle for rapid attacks against a ranging rook.
How it goes together
The king walks to 7h as in a Boat castle, and the bishop stays on 8h. The left silver comes up from 7i to 6h, beside the king, and the 6i gold steps sideways into 7i, the square the silver left. Last, the right gold steps sideways from 4i to 5i instead of up to 5h. The silver on 6h guards both golds, and both golds guard the silver. The right silver on 5g belongs to the attack, not the castle. The name comes from elmo, the program that won the 2017 World Computer Shogi Championship and played this castle again and again against ranging rooks; Japanese sources write it both elmo囲い and エルモ囲い.
Move by move
Black only, from the start position. The first nine moves are an ordinary static rook start against a ranging rook, with no gold sent to 5h. The last three build the castle.
Step through the moves, or press play.
Tap a move to jump to it. Arrow keys work once the board has focus.
Twelve moves. The gold on 7i is the point of the whole castle: it covers 8h and 8i, and the king can still run out through 6i.
What it is good against
Rook attacks along the bottom rank, and trouble in the corner. In a Boat castle the 6i gold is guarded by the king alone; on 7i the gold is guarded by the silver and the bishop as well. If the opponent’s bishop breaks through and makes a horse on 9i, the 7i gold still covers 8h and 8i, and the king has 6i to escape to, where a Boat castle king can be mated at once.
Where it breaks
It is a castle for a fast game, and not a hard one. The right silver goes forward, so only two golds and a silver defend. If your attack stalls and the ranging rook gets the initiative, it has little to offer in a long fight, and its popularity means ranging rook players have prepared against it.
When to build it
As the static rook against a ranging rook that has closed its bishop’s diagonal, with a rapid attack: the diagonal Climbing Silver with the silver on 4f (the Left Silver-46), the Pawn-45 Early Fight (４五歩早仕掛け), or a Right Fourth File Rook. From the position with the silver on 5g you can still switch to a Static Rook Anaguma instead. Professionals took it up from 2018: Fujii Sōta played it in a ranking-league game in November that year, and Watanabe Akira played it in the 68th Ōshō title match.
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.