Pinfu 「平和」 is a standard yaku. This yaku is defined by having 0 fu aside from the base 20 fu, or 30 fu in the case of a closed ron. It is worth 1 han and closed only. Under all cases, a tenpai for pinfu requires the wait pattern of ryanmen (open wait).
The winning tile completes the last sequence, which is worth 0 fu, making the hand pinfu.
In English, pinfu is sometimes referred to as "all sequences". However, the yaku is not as simple as that. Other than having an open hand, it is possible for a hand to be composed of all sequences and still not be classed as a pinfu.
The following examples are all "all sequence hands"; but they are not pinfu.
|Every tile group is a sequence, but this hand is open.
|The pair of east winds disqualifies the hand as pinfu for the dealer or for any player in the east round.
|The pair wait disqualifies this hand as pinfu.
|The dragon pair does not qualify this hand as pinfu.
|The middle wait does not qualify this hand as pinfu.
|This hand qualifies for pinfu using either 6-pin or 9-pin. However, the first tile, 3-pin, functions as tanki. Coupled with the 6-pin, it is on a 3-6 nobetan. Nevertheless, 6-pin still qualifies for pinfu, because the han increase takes precedence over fu.
To understand pinfu, players must understand the nature of fu, or mini-points. Fu are a set of points associated with hand composition. In the case of pinfu, the relevant sources of fu comes from the tile groups and the wait patterns. The only wait pinfu gains fu involves the 10 fu gained from winning with a closed ron.
Therefore, pinfu must avoid these patterns:
- Any koutsu or kantsu is worth at least 2 fu. A pinfu hand must have four shuntsu.
- Winning from a tanki, kanchan, or penchan wait is worth 2 fu.
- A pair of yakuhai, i.e., dragons, the round wind, or the seat wind, is worth 2 fu. A pinfu hand must have a valueless pair.
- An open hand worth 20 fu is counted as 30 fu. Pinfu may only be awarded to a closed hand.
As an exception, pinfu with mentsumo gains 0 fu from tsumo, or winning by self-draw. Normally, a winning tile drawn from the wall is worth 2 fu. In turn, the hand qualifies as pinfu, and these 2 fu are waived. The hand is then scored at 20 fu; and at least 2 han for menzen tsumo and pinfu. Some rule variations may not allow waiving these fu, and score such a hand as 30 fu, tsumo, without pinfu. Such variations are rare.
Essentially, pinfu is incompatible with any yaku that employs triplets, including rinshan. It is similarly incompatible with chiitoitsu, which does not use mentsu at all. On the other hand, pinfu works any sequential based yaku. As long as the hand is closed, the pair does not produce "fu", and the wait is open, then pinfu may be applied.
- Pinfu in Japanese Wikipedia