Sekinin barai
Sekinin barai 「責任払い」, or the rule of pao 「パオ」, forces a player whose discard is used to form an apparent yakuman to be liable for partial or full payment if the yakuman-holder wins. It is generally used for yakuman hands only, but certain rules also invoke pao for rinshan kaihou. Only certain types of yakuman are affected by this rule, which will depend on the ruleset.
Sekinin barai for yakuman
Point exchanges
There are two possible scenarios when it comes to how points are exchanged:
- If the yakuman is later won by tsumo, the liable player will pay the full amount of the hand, including any extra points for honba. This is as if ron was called against the liable player.
- If the yakuman is later won by ron against a non-liable player, that player will pay half the value of the hand. The liable player will pay the other half of the hand, including any extra points for honba.
If playing with rulesets that recognize multiple yakuman, sekinin barai may be invoked only on certain yakuman. Point exchanges happen independently for each yakuman scored with extra points for any honba paid only once. Honba payments are still paid by the liable player.
Example
In a round with 1 honba, the west player is liable for the south player's daisangen, and the south player wins with daisangen and tsuuiisou by tsumo, then the payments are as follows:
- East player: 16000 (part of tsuuiisou)
- West player: 32300 (full of daisangen along with honba payments) +8000 (part of tsuuiisou)
- North player: 8000 (part of tsuuiisou)
Yakuman affected by sekinin barai
Daisangen
If a player has called two groups of dragons, then calls for a group of the third dragon (upgrading to daisangen), the player who dealt into the third dragon call is affected by pao if the calling player later wins the hand.
, last: 
, formers: 
- Shimocha feeds the last set of dragon-tile triplet, he becomes the liable player.
Daisuushi
If a player has called three groups of winds, then calls for a group of the fourth (upgrading to daisuushii), the player who dealt into the fourth wind call is affected by pao if the calling player later wins the hand.
, last: 
, formers: 
- Toimen becomes liable player with confirming the fourth wind-tile triplet.
Judgement of liability
When the last group of a yakuman is called for an open kan, the discarder is still liable for pao. This may not make sense as first, since the yakuman already existed without needing the kan.
To explain how liability works with "the responsibility of completing an ensured yakuman", it is better to switch to the opponent's point of view. When a yakuman-holder has called for two groups of dragons, daisangen is not guaranteed in the opponent's eyes. Once an opponent discards the third dragon, and it is called for a kan, daisangen becomes guaranteed in the opponent's eyes. So, when discarding a tile used for a kan, pao is still invoked: from the opponent's point of view, daisangen goes from not guaranteed -> guaranteed.
Example:
Suppose a player completed a daisangen, and the hand looks like the following one in his view:
, last: , second: , first: (Main perspective)
Toimen becomes the liable player since they allowed the call from the last dragon group. From the winner's perspective, the yakuman was already completed (see below).
- , second: , first: (Main perspective)
However, from the opponent's point of view, the daisangen is not guaranteed.
, second: , first: (Opponent's view)
It is not an ensured yakuman yet.
- 1. From this point of view, the winner does not "100%" have a concealed triplet of hatsu: (This is also the reason why kamicha, the feeder of second set, doesn't need to be liable for the yakuman hand.)
- 2. The hand may also choose to discard the hatsu triplet (even if highly unlikely):
In this case, since the daiminkan of hatsu 100% confirmed a daisangen hand in the opponent's view, and killed the other possible development of being a non-yakuman:
- , last: , formers: (Opponent's perspective)
The relationship of liability is established for toimen, for becoming the feeder of last required set.
This rule also implies a useful strategy of gameplay:
- If a call confirms an ensured yakuman, the opponents should have avoided discarding such tile to get rid of the liability.
- If a call doesn't guarantee a yakuman, the opponents can discard it safely without liability.
Yakumans without sekinin barai
In general, sekinin barai does not apply to other yakuman, since other types of yakuman cannot be ensured even with all required sets are melded. A common point for these yakuman hands is that they both have some limitation of toitsu (the head pair).
Shousuushi
- Honitsu + possible yakuhai hand. Shousuushi is not ensured.
Tsuuiisou
- Toitoi + yakuhai + honitsu hand. Tsuuiisou is not ensured.
Chinroutou
- Toitoi-nomi hand. Chinroutou is not ensured.
Ryuuiisou
-
- Honitsu + yakuhai hatsu hand. Ryuuiisou is not ensured.
Sekinin barai for suukantsu
Sekinin barai is occasionally used for suukantsu: when a player has three kans, then a player discards a tile that allows the fourth kan, the feeder of the fourth kan becomes liable.
- , last: , formers:
- Shimocha becomes liable for the fact that he completed an ensured suukantsu with his discard.
Due to the criteria for recognizing sekinin barai, the precedential three kans must already exist, and the fourth kan will always be a daiminkan.
- , last: , formers:
, added kan afterwards - Toimen doesn't become liable, the melding doesn't confirm a suukantsu at that moment, even with an added kan afterwards which completed suukantsu. [note 1]
- , last:
, formers: 
- Kamicha doesn't become liable, suukantsu is not completed yet at the moment when he discarded 2-pin. It was a pon of 2-pin and the hand is only a sankantsu, even though an added kan of 2-pin happens afterwards.
Since it is difficult for an opponent to know which tile would complete the 4th kan, the pao rule is not commonly used for suukantsu. While a player may know which tiles 100% cannot be a kan, which tile exactly is uncertain (compared to daisaigen, where the third dragon always guarantees the yakuman).
Sekinin barai for rinshan kaihou
Sekinin barai is rarely used for rinshan kaihou. If a player discards a tile, and it is used for a daiminkan, pao is invoked if the daiminkan declarer wins before their next discard. This means that if the daiminkan wins immediately, or wins after making further kans, the discarder is still liable.
While uncommon, some professional mahjong associations use this rule.
References
Notes:
- ↑ Tenhou used to suggest such controversal liability relationship in early years. This rule was soon deprecated after then.
External links
- Sekinin barai in Japanese Wikipedia
- Suukantsu's pao rule in Japanese Wikipedia