Riichi Mahjong · Yakuman

Daisuushii (Big Four Winds) in Riichi Mahjong: Rules, Double Yakuman, Pao and Odds

In riichi mahjong, Daisuushii (big four winds) is a yakuman: all four winds — East, South, West and North — as triplets or quads, with any pair. It stays a yakuman when called. By default this game counts it as a double yakuman, like Mahjong Soul; with "Double yakuman" turned off in the lobby, or under Tenhou rules, it's a single yakuman.

The rules for Daisuushii

• East, South, West and North all as triplets or quads (pon, concealed triplet, open or closed kan all fine)
• Any pair: suited tiles or dragons
• A yakuman closed or open
• With the fourth wind as the pair and only three wind triplets, it's the single-yakuman shousuushii

How Daisuushii is scored

The yaku and points below are computed live by the same scoring code the game uses.

If the pair is honors too, tsuuiisou stacks on top. Yakuman don't add up with normal yaku, so the seat and round winds or toitoi inside it aren't counted.

Pao: the player who feeds the fourth wind pays

If a player already showing three wind sets calls pon (or an open kan) on the fourth wind, whoever discarded it becomes liable:

• If that hand later wins by tsumo, the liable player pays everything
• If someone else deals in, the discarder and the liable player pay half each
• If it combines with another yakuman (such as tsuuiisou), the liable player covers only the daisuushii part; the other yakuman is paid normally (shared on tsumo, by the discarder on ron)

Pao here only applies to daisangen and daisuushii. When someone shows three wind sets, never discard the last wind, even if none of it has been seen.

How it relates to other yaku

• Shousuushii: one triplet short, with the fourth wind as the pair.
• Tsuuiisou: if the pair is honors too, tsuuiisou stacks with daisuushii.
• Yakuhai: the seat and round winds inside daisuushii aren't counted, but the first step toward it is usually calling a wind that is a yaku.

Daisuushii odds

Daisuushii needs three of each wind, twelve wind tiles in all. In a 13-tile starting hand, all four winds are already a pair or better only 0% of the time; three or more, 0.014%.

Source: 1,000,000 random 13-tile deals.

Four normal-level computers played 40,000 hands on this site's table with 33,226 wins. All yakuman together came up 15 times (13 of them kokushi musou); daisuushii didn't appear once. Most wind triplets aren't yakuhai and the computers don't call them, so daisuushii almost never appears in their games.

To try it yourself, open a table of free online riichi mahjong — yakuman are scored automatically.

Daisuushii in other mahjong styles

• Taiwanese mahjong: big four winds, 16 tai (Taiwanese mahjong tai list)
• Hong Kong mahjong: big four winds is a limit hand, scored at the cap (Hong Kong mahjong fan table)
• Chinese Official (Guobiao): big four winds, 88 fan (Guobiao fan list)
• American mahjong has a whole category of hands built mostly from winds and dragons (American mahjong Winds & Dragons)

FAQ

Is Daisuushii a double yakuman?

It depends on the rules. This game's default counts it as a double yakuman, like Mahjong Soul; turn off "Double yakuman" in the lobby, or play Tenhou rules, and it's a single yakuman.

Can you call for Daisuushii?

Yes, it's still a yakuman when called. But whoever feeds the fourth wind is liable (pao).

What's the difference between Daisuushii and Shousuushii?

Daisuushii is all four winds as triplets; shousuushii is three triplets plus a wind pair, a single yakuman.

Related yaku

Shousuushii Yakuman Three wind triplets and a wind pair — a yakuman even when called. Examples, vs daisuushii, and odds. Tsuuiisou Yakuman All 14 tiles honors — a yakuman, called or closed, seven pairs allowed. Examples, combos and odds. Toitoi Closed 2 / open 2 Four triplets and a pair, still 2 han when open. Examples, scoring combos and how many starting pairs you need.