Sekinin barai

Sekinin barai 「責任払い」, or the rule of pao 「パオ」, is a liability payment imposed when a player confirms another player's yaku / yakuman. It is almost exclusively used for yakuman, but some rulesets invoke this rule for rinshan. Not all rulesets use sekinin barai in the first place.

Rule overview

Causes

Yakuman

When used for yakuman, sekinin barai is imposed when:

The yakuman-holder has made calls, so that every tile needed to complete a certain yakuman, except for 1 tile group, is in an open meld.
The discarder discards a tile needed to guarantee the yakuman, and the yakuman-holder calls it.

In this scenario, the discarder is liable for sekinin barai if the yakuman-holder wins their current hand.

Not all yakuman cause sekinin barai; the yakuman that can cause seknin barai varies by ruleset. (See below for a list.)

Rinshan

When used for rinshan kaihou, the rule works a bit differently. Sekinin bakrai is imposed when:

The discarder discards a tile that another player can open kan.
The kan-declarer wins with their rinshan draw, or wins with any rinshan draw before their next discard.

Point exchanges

When a player is liable for pao, the payment varies depending on how the yakuman-holder wins:

If the yakuman-holder wins by tsumo, the liable player will pay the full amount of the hand, including honba. This is as if ron was called against the liable player.
If the yakuman-holder wins by ron, the ronned player and liable player each pay half the value of the hand, and the liable player pays the full value of any honba.

Multiple yakuman

If playing with rulesets that recognize multiple yakuman, there are two variations on the liability payment. Either:

The hand is split: the liable player only pays for 1 yakuman's worth of value, and the rest of the hand is paid normally.
Entire hand is affected: The liability payment applies to the entire hand.

Honba payments are still paid entirely by the liable player.

Example of Tsumo

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:

If the hand is split:
- 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)
If the entire hand is affected:
- West player: 64300 (full of daisangen and tsuuiisou along with honba payments)

Example of Ron

In a round with 1 honba, the west player is liable for the south player's daisangen, and the east player deals in with daisangen and tsuuiisou, then the payments are as follows:

If the hand is split:
- East player: 32000 (full of tsuuiisou) +16000 (part of daisangen)
- West player: 16300 (part of daisangen along with honba payments)
If the entire hand is affected:
- East player: 32000 (part of daisangen and tsuuiisou)
- West player: 32300 (part of daisangen and tsuuiisou along with honba payments)

Yakuman affected by sekinin barai

Different rulesets will apply sekinin barai to different yakuman. Most rulesets include sekinin barai for daisangen and daisuushii; the other yakuman are far rarer.

Daisangen

Most rulesets with seknin barai apply it for 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

Most rulesets with seknin barai apply it for 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.

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 at the time of discard, and the fourth kan will always be an open kan.

, 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.

Nevertheless, unlike daisangen and daisuushi, the tile that determines suukantsu is not self-evident. It is difficult for an opponent to know which tile would complete the 4th kan. While a player may know which tiles 100% cannot be a kan, which tile exactly is uncertain. Based on the above reasons, the pao rule is not commonly used for suukantsu.

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.

Judgement of liability

Sekinin barai exists to punish "foolish" discards that ensure a yakuman.

However, when the last group of a yakuman is called for an open kan, the discarder is still liable for pao. Even though the yakuman already existed without needing the kan, pao is still applied.

To explain how liability works in terms of "the player is responsible for ensuring a 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.

Yakuman 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).