Furiten
Furiten, meaning sacred discard, is a hand status. A player in tenpai is furiten if he could win on an earlier self-discarded tile, or if he has recently ignored to win by ron. Players in furiten may still win by tsumo, but not by ron.
Rules
A player with a tenpai hand is furiten if at least one of the conditions below applies.
- Players in furiten may not win by ron, even if they have a yaku. Declaring ron while in furiten is penalized with a chombo payment.
- Players in furiten may still win by tsumo.
- After riichi declarations, all discarded tiles after the riichi discard may apply to furiten.
- A player may pass the opportunity to declare ron and is subject to furiten until the next turn to draw/discard.
The furiten rule does not consider yaku. Sometimes, a hand can be completed with several tiles, but only some of them provide a yaku, others would produce a yakuless hand. If a yakuless tile appears, it must be ignored, because a winning hand must contain a yaku. The player must remain temporarily furiten.
Discard-based furiten
A player is furiten, if a winning tile is present in one own's discard pile. It does not matter whether this tile would have provided a yaku or not. Tiles turned sideways within open melds are considered part of their discarder's discard pile.
As long as the player has not declared riichi, furiten can be avoided by altering the hand and changing tile waits.
, waiting on 
, , or 
This hand has three different tiles to wait on. If the player has a 2-pin in his own discard pile, he is furiten and may not win by ron on any tile. Even if a 5-pin or 8-pin gets discarded by an opponent, he may not call ron.
Permanent furiten
A riichi declarer is furiten when he has missed a chance to call ron against a winning tile after his riichi declaration. The ignored winning tile may have been a discarded tile, or a tile used to extend a minkou to a shominkan.
The player will remain furiten for the rest of the hand. He cannot call ron on any tile, even if it is a different tile than the ignored one. This rule requires knowledge of all own possible waits.
Temporary furiten
The ability to declare ron and win a hand is an optional call. Instead, a player may decline the call to win. By declining this call, a player opts to resume play rather than choose to win the hand at that specific time. Upon doing so, The player is then temporarily furiten, until the next tile draw. Some rules additionally cancel temporary furiten on any tile call by any player.
A player who has not declared riichi may also ignore a hand-completing tile and not call ron on it. Again, this may have been a discarded tile or the tile for a shominkan.
Strategy
Furiten is often used to defend against opponents. By discarding tiles that are also visible in an opponent's discard pile, a player can avoid a ron call by that opponent.
Dealing with furiten
Sometimes, it may be necessary to deliberately place the hand in furiten. Often times, this is the result of developing the hand and defending simultaneously.