Rules · 王手 ōte
When the king is attacked.
A king is in check (王手, ōte) when an enemy piece could capture it on the next move. The player in check must end that threat with their very next move. There are three ways to do it, and in shogi the third, blocking, can use a piece from your hand.
The three answers
Take the checking piece, move the king to a square nobody attacks, or put a piece between the king and a checker that attacks from a distance. Only a rook, a bishop or a lance checks from a distance (a dragon and a horse keep that reach; a promoted lance moves like a gold), so only those checks can be blocked.
Blocking with a drop (合駒 aigoma)
A piece put between the king and the checker is called 合駒 (aigoma). In chess only a piece already on the board can do it; in shogi any piece in your hand can be dropped on the line, which is why a long-range check against a player holding pieces is so often harmless. A drop that blocks must still be a legal drop: no second pawn on a file, no piece on a square it could never leave.
A knight check cannot be blocked
A knight jumps, so there is no square between it and the king to drop anything on. The same is true of every piece that checks from the next square. Against those, only the other two answers are left: take the checker or move the king.
Double check (両王手 ryō-ōte)
When two pieces check at once, taking one or blocking one still leaves the other. The only answer is to move the king. That is what makes double check so strong, and why a move that uncovers one check while giving another is worth looking for.
Discovered check (開き王手 aki-ōte)
Moving a piece out of the line between your long-range piece and the enemy king gives check without the moving piece doing anything. The piece that moved is then free to attack something else, and if it gives check too, it is double check.
Answering check with check (逆王手 gyaku-ōte)
A reply to check may give check back, for example a piece put between the kings that attacks the other king along the same line. It is legal as long as your own king is out of check once it is played.
Nobody has to say “check”
Chess players sometimes announce check. In shogi there is no such rule, and saying 王手 at the board is not the custom in serious games. Noticing the check is each player’s own job, and leaving your king in check is an illegal move that loses.
When there is no answer
If none of the three answers works, the king is checkmated (詰み, tsumi) and the game is over. The shapes checkmates take most often are on mating patterns.
Find the answer.
The practice bot checks you often at the low levels. Each time, look for all three answers before you pick one.