Atozuke

Definition

Atozuke (後付け) refers to winning with a yaku that only becomes valid after the winning tile is drawn or called. The yaku cannot be confirmed as complete until the final tile that completes the hand is obtained, at which point all conditions for that yaku are satisfied simultaneously.

Detailed Explanation

In mahjong, most yaku are built progressively throughout a hand. However, atozuke yaku have a unique characteristic: they cannot be verified as valid until the very moment of winning. This is distinct from yaku that are “locked in” earlier in the hand’s development.

The most common example of atozuke is tanyao (all simples). A player might be collecting tiles 2 through 8 in various suits, but tanyao is not confirmed until the winning tile is drawn or called. If a player is one tile away from completing tanyao and draws a terminal or honor tile instead, they cannot claim tanyao for that hand—the yaku was never actually formed.

Another example is pinfu (no points). A pinfu hand must have no melds worth points and must win on an open wait. These conditions can only be fully verified at the moment of winning. Similarly, iipeikou (two identical sequences) requires matching pairs of melon that must all be confirmed before declaring victory.

The concept of atozuke is important for understanding when yaku become “locked” versus when they remain conditional. In some rule sets, declaring a yaku too early or incorrectly can result in penalties. Atozuke yaku protect players from this issue because no declaration is necessary until the actual winning moment.

It’s worth noting that atozuke applies primarily to standard yaku in Japanese mahjong variants. Different regional rule sets may handle yaku confirmation differently, but the principle remains consistent: certain yaku cannot exist in a valid hand until all conditions are simultaneously satisfied by the winning tile.

Usage Example

Consider a player building toward tanyao. Their current melds include:

• Pung of 3-man
• Chow of 4-5-6-pin
• Pung of 7-sou
• Pair of 5-man

With one tile needed to complete the hand, they need either a 2, 3, 4, or 8 in any suit (assuming the hand structure allows). If they draw a 1-man (a terminal), they cannot win with tanyao because tanyao requires all simples. The yaku was never actually valid—it was only a possibility until the winning tile was drawn.

If instead they draw a 2-pin, completing their hand, tanyao is now confirmed. The winning tile “locked in” the yaku, making it valid retroactively for the entire hand. This is atozuke in action: the yaku only became real at the moment of winning.

Another scenario: a player is one tile away from completing two identical sequences (iipeikou). They have two chows of 2-3-4 in different suits and need one more tile to complete a second identical sequence. Until that final tile is drawn, iipeikou is not confirmed. When the winning tile completes the second sequence, iipeikou becomes valid through atozuke.

Related Terms

Sakizuke (先付け) – The opposite of atozuke; yaku that are confirmed before the winning tile is drawn. Once all conditions are met, the yaku is “locked in.”

Yaku – The hand patterns and conditions that determine winning hands and their point values. Atozuke yaku are a subset of all possible yaku.

Agari (上がり) – Winning a hand. The moment when atozuke yaku become valid.

Meld – A group of three or four tiles (pung, chow, or kong). Melds are used to construct yaku conditions.

Kuitan – A rule variant allowing tanyao to be won on a melded hand, which affects how atozuke applies in some rule sets.