Yaku

Yaku 「役」 are specific hand patterns or conditions needed in order to score a hand. In a sense, they are synonymous to "poker hands". Yet, unlike poker hands, yaku are worth specific "han values"; and various yaku may be combined together into one hand. basic mahjong knowledge involves learning the yaku, but it is not expected of new players to know them.

Most importantly, every hand must include at least one yaku, in order to count as a winning hand.

Han

Main article: Scoring

Each yaku is assigned han values. Most have static values, regardless of the hand being closed or open. However, some decrease in han value while being open. Furthermore, some also require hands to remain closed in order to count. For hands to maximize the total han value, different yaku may be combined into a single hand.

Open vs closed

Main article: Kuisagari

Various yaku are affected by the hand's state of being open or closed. After using the different tile calls, a yaku may be affected in terms of han value or even validity. Various yaku, and even yakuman, are restricted to be closed only. Others, they remain valid but their value is decreased by 1-han. As for the rest, it is irrelevant whether the hand is open or closed.

Yaku types

The different yaku focus on different types of patterns and circumstances. They are mostly derived from the tiles within one's hand. A number of yaku also involve the state of one's hand pertaining to the timing of certain tile draws and discards.

Circumstantial

Two yaku specifically are based on the current state of tenpai, as well as particular actions of other players.

• Chankan

Calling kan with a winning tile.

• Houtei raoyui

Discarding an unsafe tile as the last discard, which happens to be a winning tile.

Discretionary

• Riichi

This is the only yaku, by which players have the option to declare or not. Otherwise, hands may possibly win without it, if it remains closed with other valid yaku.

Honor based

Honor based tiles depends on the use of honor tile groups. Each of these cases also are mixed with the numbered tiles.

• Honitsu

Honor tiles with one suit.

• Honroutou

Honor tiles with terminals.

• Shousangen

Specific collection of all three dragon types.

• Tanyao

No honors or (terminal) are used.

• Yakuhai

Specific collection of any dragon, seat wind, or round wind tiles.

Luck based

Luck based yaku focuses on specific instances regarding tile draws. Sometimes with the exception of ippatsu, other players have no bearing on the outcome of these tile draws.

• Double riichi

This is essentially riichi, but with the added luck of the hand being tenpai upon the initial tile deal, or the opening hand.

• Ippatsu

Winning before the next tile draw after riichi.

• Haitei raoyue

Winning with the last tile draw.

• Rinshan kaihou

Drawing a winning tile after a kan call.

Sequential

These yaku either require sequential tile groups.

• Iipeikou

By definition, this yaku uses two-identical sequences.

• Ittsu

A complete string of 1-9 tile naturally use sequences.

• Pinfu

Every tile group must be a sequence.

• Ryanpeikou

By definition, this yaku uses two-identical sequences two times.

• Sanshoku

By definition, this yaku uses three identically numbered sequences across the three suits.

Terminal based

These yaku revolve around terminals, or complete lack thereof.

• Chanta

Every tile group with an honor or terminal.

• Honroutou

Only honor and terminal groups.

• Junchan

Every tile group with a terminal.

• Nagashi mangan

Every discarded tile is either a terminal or honor

• Tanyao

No terminals (or honors) are used.

Triplet

These yaku require at least one triplet in order to be valid.

• Honroutou

Can only be formed using triplets.

• Sanankou

Three closed triplets.

• Sankantsu

Requires three quads, which are considered as triplets plus one extra.

• Sanshoku doukou

Needs three identically numbered triplets across the three suits.

• Shousangen

Triplets of dragon tiles.

• Toitoi

Every tile group is a triplet.

• Yakuhai

Counted when the hand contains a triplet of a valid honor tile, namely: any dragon triplet, appropriate seat wind, or the current round wind.

Yakuman

Main article: Yakuman

Yakuman is a special class of yaku, by which the pattern itself is awarded the maximum point limit for a single hand pattern.

Combining yaku

Main article: Yaku compatability

Different yaku may be implemented into a single hand. By doing so, the values applied to the different yaku also combine. In short, they stack. This aspect of the game is key towards developing larger scoring hands. With dora, the stacking effect becomes even greater.

External links

• 役_(麻雀)

Yaku in Japanese Wikipedia

• Japanese mahjong yaku

Wikipedia listing

• Yaku frequency among Tenhou.net players (Japanese)

Lists all the yaku occurrences in Tenhou.net by percentages and by room

• Yaku short list

Pointing out which yaku to learn first