noun
dai shogi; large shogi variant
A historical large-board shogi variant played on a 15×15 board. Not commonly played today; mainly encountered in historical or game-study contexts.
大将棋は十五掛ける十五の盤で遊ぶ将棋の一種です。
Dai shogi is a kind of shogi played on a fifteen-by-fifteen board.
彼は古い将棋のルールを研究していて、大将棋にも詳しい。
He studies old shogi rules and is knowledgeable about dai shogi as well.
Another historical large-board shogi variant (12×12). 大将棋 is even larger at 15×15.
From 大 (dai, 'large') + 将棋 (shōgi, 'shogi'). The name reflects the larger board size compared to standard shogi.