Riichi Mahjong · Yakuman

Shousuushii (Little Four Winds) in Riichi Mahjong: Rules, Examples and Odds

In riichi mahjong, Shousuushii (little four winds) is a yakuman: three of the four winds (East, South, West, North) as triplets or quads, the fourth wind as the pair, and any one set to finish. It stays a yakuman when called.

The rules for Shousuushii

• Three winds as triplets or quads (pon, concealed triplet, open or closed kan all fine)
• The fourth wind as the pair
• The last set is free: a sequence, suited tiles or a dragon
• A yakuman closed or open; which wind is your seat or round wind doesn't matter

All four winds as triplets is daisuushii. Two wind triplets plus a wind pair has no special yaku in riichi mahjong — it only depends on whether those triplets are yakuhai (seat or round wind).

How Shousuushii is scored

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

Yakuman don't add up with normal yaku, so the seat and round winds, honitsu or toitoi inside shousuushii aren't counted.

Shousuushii vs Daisuushii

Pao (liability) here only applies to daisangen and daisuushii: feeding someone their third wind set carries no liability; feeding the fourth (which locks in daisuushii) does.

How it relates to other yaku

• Daisuushii: make the pair wind a triplet too and it's daisuushii. If your shousuushii waits on a shanpon with the fourth wind, winning on that wind turns it into daisuushii.
• Tsuuiisou: if the last set is honors too, it's a double yakuman.
• Honitsu: winds plus one suit is the most common shousuushii shape, but honitsu isn't counted on top of a yakuman.

Shousuushii odds

How many wind pairs you start with

Shousuushii needs at least two of every wind and three of three of them. In a 13-tile starting hand, three or more winds are a pair or better about 0.014% of the time; all four only 0%.

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

How often it happens in play

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); shousuushii didn't appear once. Most wind triplets aren't yakuhai and the computers don't call them, so shousuushii is very rare in their games.

Which hands suit Shousuushii

• Pairs of three or more winds at the start: if your seat or round wind is among them, the first pon already gives you a yaku and you can call freely.
• Call the off-winds too: West or North with no value are usually your first discards; for shousuushii you keep them to pon.
• Others will defend: once two or three wind sets are showing, nobody discards winds, and the last pair or triplet usually has to be drawn.

To try it, open a table of online riichi mahjong — the computers play with you and score the yakuman for you.

Shousuushii in other mahjong styles

• Taiwanese mahjong: little four winds, 8 tai (Taiwanese mahjong tai list)
• Hong Kong mahjong: little four winds is a limit hand, scored at the cap (Hong Kong mahjong fan table)
• Chinese Official (Guobiao): little four winds, 64 fan (Guobiao fan list)
• American mahjong has a whole category of hands built mostly from winds and dragons (American mahjong Winds & Dragons)

FAQ

How many han is Shousuushii?

Shousuushii is a yakuman, so it isn't counted in han, and it stays a yakuman when called. With tsuuiisou it's a double yakuman.

What's the difference between Shousuushii and Daisuushii?

Shousuushii is three wind triplets plus a wind pair; daisuushii is all four winds as triplets, a double yakuman by default in this game.

Does Shousuushii need my seat or round wind?

No. Shousuushii is a yaku by itself, whichever winds are yours. But if you pon off-winds and the hand doesn't come together, you're left with no yaku, so calling your seat or round wind first is safer.

Related yaku

Daisuushii Yakuman Triplets of all four winds — a yakuman even when called; double yakuman by default. Example, pao and odds. Tsuuiisou Yakuman All 14 tiles honors — a yakuman, called or closed, seven pairs allowed. Examples, combos and odds. Honitsu Closed 3 / open 2 One suit plus honors — 3 han closed, 2 open. Examples, honitsu vs chinitsu, and how many tiles you need to go for it.