Fouls in Shogi: Nifu, Dead Pieces and Ignoring Check

The fouls of shogi are collected in Article 10 of the Japan Shogi Association’s rules for official games (in Japanese). The first clause lists thirteen items, and a player who commits any of them loses on the spot. There is no warning and playing on, as in football. The game ends at the moment of the foul.

In this post I go through the ones a beginner should know, roughly in the order they tend to happen.

Nifu (two pawns)

Nifu means having two of your own unpromoted pawns on the same file. The rules call it placing two pawns of the same player on the same file.

It happens most often when dropping a pawn from your hand. You drop one on a file where you already have a pawn. When your pawn on the board has advanced near the opponent’s camp, it is easy to miss that it is on the same file.

A promoted pawn, a tokin, does not count as a pawn. Dropping a pawn on a file with a tokin is not a foul.

Pieces with no legal move

This is placing a piece on a square from which it can never move again. The rules describe it as moving a piece on the board, or dropping a piece from hand, onto a square where it has nowhere to go.

Three pieces are affected. Pawns and lances can only move forward, so on the farthest rank they are stuck. A knight jumps two squares forward, so on the last two ranks it is stuck.

When a piece moves onto such a square, it is not a foul if it promotes. A pawn or lance reaching the last rank, or a knight reaching the last two ranks, must promote. A dropped piece cannot promote, so it cannot be dropped there at all.

Uchifuzume (pawn-drop mate)

This is mating the opponent’s king by dropping a pawn from your hand. The rules call it dropping a pawn to give a check that cannot be escaped.

Checking with a dropped pawn is not a foul in itself. Mating by pushing a pawn already on the board is not a foul either. It is only a foul when the dropped pawn gives a check the king cannot get out of. How to tell these shapes apart is in Uchifuzume Explained.

Ignoring check

This is playing some other move while your king is in check, instead of dealing with it. The rules list it together with moving your own king onto a square attacked by an opponent’s piece.

Shogi is not a game where you capture the king. It ends when the king cannot escape. So a move that leaves your own king open to capture loses as soon as you play it.

Missing a check is common for beginners. The lines of distant bishops, rooks and lances are especially easy to overlook. You are pleased to capture a piece, and that very move has put your king on the line of a rook.

Perpetual check

When the same position appears four times, it is called sennichite. Under Article 8 of the rules, sennichite has no winner, and the game is replayed with colours swapped. Sennichite itself is not a foul.

But if every move by one side during that sequence was a check, it is a perpetual check sennichite, which is a foul, and the side giving the checks loses. In other words, you cannot save a lost game simply by checking forever.

Moving twice, taking back a move, and others

Article 10 also lists fouls such as these:

• Moving twice: the same player making two moves in a row
• Taking back a move: cancelling a move once it is complete
• Wrong colours: mixing up who plays first at the start
• Running out of time: failing to move within the time limit or byoyomi
• Using advice, or analysing on another board
• Impossible moves: for example, moving a piece the wrong way

In casual games, moving twice or taking back a move may be treated lightly. In official games, both lose on the spot.

If a foul goes unnoticed and play continues, it still counts if it is found before the game ends: play goes back to the point of the foul and the offender loses. If it is found after the game, the player who committed it loses regardless of the result (Article 10, clauses 2 and 3).

The fouls kids make most

Three that often come up in games between children are nifu, ignoring check, and pieces with no legal move. None of them come from not knowing the rules. They happen when the child is not seeing the whole board: missing where their own pawns are, missing the line of a distant piece, or not asking “where can this piece go next?”

There is also a view that it works better to explain each foul when it actually happens than to teach them all at once at the start. I wrote about this in Teaching Shogi to Kids as well. Losing by a foul stings, so children remember what they hear at that moment. Once they start playing under official rules, for example at a tournament, it is reassuring to go through the list in this post once.

In Mindsports, fouls cannot be played

In the shogi of StudyX Mindsports, moves that would be fouls cannot be selected on the board. You cannot drop on a file that would make nifu, on a square that would be pawn-drop mate, or on a square where the piece could never move. When a piece moves onto such a square, only the promoting move is offered. Moves that leave your own king open to capture cannot be played either, so ignoring check never happens.

For a beginner, this means you can play without worrying about fouls, but on a real board you will need to watch for them yourself. The app also has Undo for practice. Since it is a foul in official play, it is something for practice only.

The shogi beginner lessons teach how the pieces move and the rules through tap-to-answer quizzes. After the lessons you can play the CPU from Lv.1 to Lv.50. It goes up one level when you win and down one when you lose. The games and beginner lessons are free, with ads. How the pieces move is in How Shogi Pieces Move, and how to use the app is in Getting Started with StudyX Mindsports.